A lexicon (plural: lexicons, rarely lexica) is the

vocabulary A vocabulary (also known as a lexicon) is a set of words, typically the set in a language or the set known to an individual. The word ''vocabulary'' originated from the Latin , meaning "a word, name". It forms an essential component of languag ...

of a

language Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed language, signed forms, and may also be conveyed through writing syste ...

or branch of

knowledge Knowledge is an Declarative knowledge, awareness of facts, a Knowledge by acquaintance, familiarity with individuals and situations, or a Procedural knowledge, practical skill. Knowledge of facts, also called propositional knowledge, is oft ...

(such as

nautical Seamanship is the art, competence, and knowledge of operating a ship, boat or other craft on water. The'' Oxford Dictionary'' states that seamanship is "The skill, techniques, or practice of handling a ship or boat at sea." It involves topic ...

medical Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

). In

linguistics Linguistics is the scientific study of language. The areas of linguistic analysis are syntax (rules governing the structure of sentences), semantics (meaning), Morphology (linguistics), morphology (structure of words), phonetics (speech sounds ...

, a lexicon is a language's inventory of

lexeme A lexeme () is a unit of lexical meaning that underlies a set of words that are related through inflection. It is a basic abstract unit of meaning, a unit of morphological analysis in linguistics that roughly corresponds to a set of forms ta ...

s. The word ''lexicon'' derives from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

word (), neuter of () meaning 'of or for words'. Linguistic theories generally regard human languages as consisting of two parts: a lexicon, essentially a catalogue of a language's words (its wordstock); and a

grammar In linguistics, grammar is the set of rules for how a natural language is structured, as demonstrated by its speakers or writers. Grammar rules may concern the use of clauses, phrases, and words. The term may also refer to the study of such rul ...

, a system of rules which allow for the combination of those words into meaningful sentences. The lexicon is also thought to include

bound morpheme In linguistics, a bound morpheme is a morpheme (the elementary unit of morphosyntax) that can appear only as part of a larger expression, while a free morpheme (or unbound morpheme) is one that can stand alone. A bound morpheme is a type of bound f ...

s, which cannot stand alone as words (such as most

affix In linguistics, an affix is a morpheme that is attached to a word stem to form a new word or word form. The main two categories are Morphological derivation, derivational and inflectional affixes. Derivational affixes, such as ''un-'', ''-ation' ...

es). In some analyses,

compound word In linguistics, a compound is a lexeme (less precisely, a word or Sign language, sign) that consists of more than one Word stem, stem. Compounding, composition or nominal composition is the process of word formation that creates compound lexemes. C ...

s and certain classes of

idiom An idiom is a phrase or expression that largely or exclusively carries a Literal and figurative language, figurative or non-literal meaning (linguistic), meaning, rather than making any literal sense. Categorized as formulaic speech, formulaic ...

atic expressions,

collocation In corpus linguistics, a collocation is a series of words or terms that co-occur more often than would be expected by chance. In phraseology, a collocation is a type of compositional phraseme, meaning that it can be understood from the words t ...

s and other

phraseme A phraseme, also called a set phrase, fixed expression, multiword expression (in computational linguistics), or idiom, is a multi-word or multi-morphemic utterance whose components include at least one that is selectionally constrained or restri ...

s are also considered to be part of the lexicon.

Dictionaries A dictionary is a listing of lexemes from the lexicon of one or more specific languages, often arranged Alphabetical order, alphabetically (or by Semitic root, consonantal root for Semitic languages or radical-and-stroke sorting, radical an ...

are lists of the lexicon, in alphabetical order, of a given language; usually, however, bound morphemes are not included.

Size and organization

Items in the lexicon are called lexemes, lexical items, or word forms. Lexemes are not atomic elements but contain both phonological and morphological components. When describing the lexicon, a reductionist approach is used, trying to remain general while using a minimal description. To describe the size of a lexicon,

s are grouped into lemmas. A lemma is a group of lexemes generated by

inflectional morphology In linguistic morphology, inflection (less commonly, inflexion) is a process of word formation in which a word is modified to express different grammatical categories such as tense, case, voice, aspect, person, number, gender, mood, ...

. Lemmas are represented in dictionaries by headwords that list the

citation form In morphology and lexicography, a lemma (: lemmas or lemmata) is the canonical form, dictionary form, or citation form of a set of word forms. In English, for example, ''break'', ''breaks'', ''broke'', ''broken'' and ''breaking'' are forms of the ...

s and any irregular forms, since these must be learned to use the words correctly. Lexemes derived from a word by derivational morphology are considered new lemmas. The lexicon is also organized according to open and closed categories. Closed categories, such as

determiners Determiner, also called determinative (abbreviated ), is a term used in some models of grammatical description to describe a word or affix belonging to a class of noun modifiers. A determiner combines with a noun to express its reference. Exampl ...

pronoun In linguistics and grammar, a pronoun (Interlinear gloss, glossed ) is a word or a group of words that one may substitute for a noun or noun phrase. Pronouns have traditionally been regarded as one of the part of speech, parts of speech, but so ...

s, are rarely given new lexemes; their function is primarily

syntactic In linguistics, syntax ( ) is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure (constituency ...

. Open categories, such as

noun In grammar, a noun is a word that represents a concrete or abstract thing, like living creatures, places, actions, qualities, states of existence, and ideas. A noun may serve as an Object (grammar), object or Subject (grammar), subject within a p ...

s and

verb A verb is a word that generally conveys an action (''bring'', ''read'', ''walk'', ''run'', ''learn''), an occurrence (''happen'', ''become''), or a state of being (''be'', ''exist'', ''stand''). In the usual description of English, the basic f ...

s, have highly active generation mechanisms and their lexemes are more

semantic Semantics is the study of linguistic Meaning (philosophy), meaning. It examines what meaning is, how words get their meaning, and how the meaning of a complex expression depends on its parts. Part of this process involves the distinction betwee ...

in nature.

Lexicalization and other mechanisms in the lexicon

A central role of the lexicon is documenting established ''lexical norms and conventions''.

Lexicalization In linguistics, lexicalization is the process of adding words, set phrases, or word patterns to a language's lexicon. Whether '' word formation'' and ''lexicalization'' refer to the same process is controversial within the field of linguistics. M ...

is the process by which new words, having gained widespread usage, enter the lexicon. Since lexicalization may modify lexemes phonologically and morphologically, it is possible that a single etymological source may be inserted into a single lexicon in two or more forms. These pairs, called a doublet, are often close semantically. Two examples are ''

aptitude An aptitude is a component of a competence to do a certain kind of work at a certain level. Outstanding aptitude can be considered "talent", or "skill". Aptitude is inborn potential to perform certain kinds of activities, whether physical or ...

'' versus ''

attitude Attitude or Attitude may refer to: Philosophy and psychology * Attitude (psychology), a disposition or state of mind ** Attitude change * Propositional attitude, a mental state held towards a proposition Science and technology * Orientation ...

'' and '' employ'' versus '' imply''. The mechanisms, not mutually exclusive, are: * Innovation, the planned creation of new roots (often on a large-scale), such as ''slang'', ''branding''. * Borrowing of foreign words. *

Compounding In the field of pharmacy, compounding (performed in compounding pharmacies) is preparation of custom medications to fit unique needs of patients that cannot be met with mass-produced formulations. This may be done, for example, to provide medic ...

(composition), the combination of lexemes to make a single word. *

Abbreviation An abbreviation () is a shortened form of a word or phrase, by any method including shortening (linguistics), shortening, contraction (grammar), contraction, initialism (which includes acronym), or crasis. An abbreviation may be a shortened for ...

of compounds. *

Acronyms An acronym is a type of abbreviation consisting of a phrase whose only pronounced elements are the initial letters or initial sounds of words inside that phrase. Acronyms are often spelled with the initial Letter (alphabet), letter of each wor ...

, the reduction of compounds to their initial letters, such as

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

and laser (from "LASER"). *

Inflection In linguistic Morphology (linguistics), morphology, inflection (less commonly, inflexion) is a process of word formation in which a word is modified to express different grammatical category, grammatical categories such as grammatical tense, ...

, a morphology change with a category, such as a number or tense. *

Derivation Derivation may refer to: Language * Morphological derivation, a word-formation process * Parse tree or concrete syntax tree, representing a string's syntax in formal grammars Law * Derivative work, in copyright law * Derivation proceeding, a ...

, a morphological change resulting in a change of category. *

Agglutination In linguistics, agglutination is a morphology (linguistics), morphological process in which words are formed by stringing together morphemes (word parts), each of which corresponds to a single Syntax, syntactic feature. Languages that use agglu ...

, the compounding of morphemes into a single word.

Neologisms (new words)

Neologism In linguistics, a neologism (; also known as a coinage) is any newly formed word, term, or phrase that has achieved popular or institutional recognition and is becoming accepted into mainstream language. Most definitively, a word can be considered ...

s are new lexeme candidates which, if they gain wide usage over time, become part of a language's lexicon. Neologisms are often introduced by children who produce erroneous forms by mistake. Other common sources are slang and advertising.

Neologisms that maintain the sound of their external source

There are two types of borrowings (neologisms based on external sources) that retain the sound of the source language material: * Borrowing using the source language lexical item as the basic material for the neologization: guestwords, foreignisms and loanwords * Borrowing using a target language lexical items as the basic material for the neologization: phono-semantic matching, semanticized phonetic matching and phonetic matching.

Guestwords, foreignisms and loanwords

The following are examples of external lexical expansion using the source language lexical item as the basic material for the neologization, listed in decreasing order of phonetic resemblance to the original lexical item (in the source language): * Guestword (in German: ''Gastwort''): unassimilated borrowing. * Foreignism (in German: ''Fremdwort''): foreign word, e.g. phonetic adaptation. * Loanword (in German: ''Lehnwort''): totally assimilated borrowing, e.g. morphemic adaptation.

Phono-semantic matches, semanticized phonetic matches and phonetic matches

The following are examples of simultaneous external and internal lexical expansion using target language lexical items as the basic material for the neologization but still resembling the sound of the lexical item in the source language: *

Phono-semantic matching Phono-semantic matching (PSM) is the incorporation of a word into one language from another, often creating a neologism, where the word's non-native quality is hidden by replacing it with phonetically and semantically similar words or roots f ...

(PSM): the target language material is originally similar to the source language lexical item both phonetically and semantically. * Semanticized phonetic matching (SPM): the target language material is originally similar to the source language lexical item phonetically, and only in a loose way semantically. * Phonetic matching (PM): the target language material is originally similar to the source language lexical item phonetically but not semantically.

Role of morphology

Another mechanism involves generative devices that combine morphemes according to a language's rules. For example, the

suffix In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns and adjectives, and verb endings, which form the conjugation of verbs. Suffixes can ca ...

"-able" is usually only added to

transitive verb A transitive verb is a verb that entails one or more transitive objects, for example, 'enjoys' in ''Amadeus enjoys music''. This contrasts with intransitive verbs, which do not entail transitive objects, for example, 'arose' in ''Beatrice arose ...

s, as in "readable" but not "cryable".

Compounding

A compound word is a lexeme composed of several established lexemes, whose semantics is not the sum of that of their constituents. They can be interpreted through

analogy Analogy is a comparison or correspondence between two things (or two groups of things) because of a third element that they are considered to share. In logic, it is an inference or an argument from one particular to another particular, as oppose ...

, common sense and, most commonly, context. Compound words can have simple or complex morphological structures. Usually, only the head requires inflection for agreement. Compounding may result in lexemes of unwieldy proportion. This is compensated by mechanisms that reduce the length of words. A similar phenomenon has been recently shown to feature in social media also where hashtags compound to form longer-sized hashtags that are at times more popular than the individual constituent hashtags forming the compound.Suman Kalyan Maity, Ritvik Saraf and Animesh Mukherjee (2016). #Bieber + #Blast = #BieberBlast: Early Prediction of Popular Hashtag Compounds. In ''ACM CSCW'', San Francisco, CA. Compounding is the most common of word formation strategies cross-linguistically.

Diachronic mechanisms

Comparative historical linguistics studies the evolution of languages and takes a

diachronic Synchrony and diachrony are two complementary viewpoints in linguistic analysis. A ''synchronic'' approach - from ,("together") + ,("time") - considers a language at a moment in time without taking its history into account. In contrast, a ''diac ...

view of the lexicon. The evolution of lexicons in different languages occurs through a parallel mechanism. Over time historical forces work to shape the lexicon, making it simpler to acquire and often creating an illusion of great regularity in language. * Phonological assimilation, the modification of loanwords to fit a new language's sound structure more effectively. If, however, a loanword sounds too "foreign", inflection or derivation rules may not be able to transform it. *

Analogy Analogy is a comparison or correspondence between two things (or two groups of things) because of a third element that they are considered to share. In logic, it is an inference or an argument from one particular to another particular, as oppose ...

, where new words undergo inflection and derivation analogous to that of words with a similar sound structure. * Emphasis, the modification of words' stress or accent. *

Metaphor A metaphor is a figure of speech that, for rhetorical effect, directly refers to one thing by mentioning another. It may provide, or obscure, clarity or identify hidden similarities between two different ideas. Metaphors are usually meant to cr ...

, a form of semantic extension.

Second-language lexicon

The term "lexicon" is generally used in the context of a single language. Therefore, multi-lingual speakers are generally thought to have multiple lexicons. Speakers of language variants (

Brazilian Portuguese Brazilian Portuguese (; ; also known as pt-BR) is the set of Variety (linguistics), varieties of Portuguese language native to Brazil. It is spoken by almost all of the 203 million inhabitants of Brazil and widely across the Brazilian diaspora ...

and

European Portuguese European Portuguese (, ), also known as Lusitanian Portuguese () or as the Portuguese (language) of Portugal (), refers to the dialects of the Portuguese language spoken in Portugal. The word "European" was chosen to avoid the clash of "Portugues ...

, for example) may be considered to possess a single lexicon. Thus a '' cash dispenser'' (British English) as well as an

automatic teller machine An automated teller machine (ATM) is an electronic telecommunications device that enables customers of financial institutions to perform financial transactions, such as cash withdrawals, deposits, funds transfers, balance inquiries or account ...

or ATM in American English would be understood by both American and British speakers, despite each group using different dialects. When linguists study a lexicon, they consider such things as what constitutes a word; the word/

concept A concept is an abstract idea that serves as a foundation for more concrete principles, thoughts, and beliefs. Concepts play an important role in all aspects of cognition. As such, concepts are studied within such disciplines as linguistics, ...

relationship; lexical access and lexical access failure; how a word's

phonology Phonology (formerly also phonemics or phonematics: "phonemics ''n.'' 'obsolescent''1. Any procedure for identifying the phonemes of a language from a corpus of data. 2. (formerly also phonematics) A former synonym for phonology, often pre ...

syntax In linguistics, syntax ( ) is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure (constituenc ...

, and meaning intersect; the

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

-word relationship; vocabulary structure within a given language; language use (

pragmatics In linguistics and the philosophy of language, pragmatics is the study of how Context (linguistics), context contributes to meaning. The field of study evaluates how human language is utilized in social interactions, as well as the relationship ...

);

language acquisition Language acquisition is the process by which humans acquire the capacity to perceive and comprehend language. In other words, it is how human beings gain the ability to be aware of language, to understand it, and to produce and use words and s ...

; the history and evolution of words (

etymology Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...

); and the relationships between words, often studied within

philosophy of language Philosophy of language refers to the philosophical study of the nature of language. It investigates the relationship between language, language users, and the world. Investigations may include inquiry into the nature of Meaning (philosophy), me ...

. Various models of how lexicons are organized and how words are retrieved have been proposed in

psycholinguistics Psycholinguistics or psychology of language is the study of the interrelation between linguistic factors and psychological aspects. The discipline is mainly concerned with the mechanisms by which language is processed and represented in the mind ...

neurolinguistics Neurolinguistics is the study of Nervous system, neural mechanisms in the human brain that control the comprehension, production, and acquisition of language. As an interdisciplinary field, neurolinguistics draws methods and theories from fie ...

and

computational linguistics Computational linguistics is an interdisciplinary field concerned with the computational modelling of natural language, as well as the study of appropriate computational approaches to linguistic questions. In general, computational linguistics ...