Latino sine flexione (" Latin without inflections"), Interlingua de Academia pro Interlingua (IL de ApI) or Peano's Interlingua (abbreviated as IL), is an
international auxiliary language An international auxiliary language (sometimes acronymized as IAL or contracted as auxlang) is a language meant for communication between people from all different nations, who do not share a common first language. An auxiliary language is primar ...
compiled by the Academia pro Interlingua under chairmanship of the Italian mathematician
Giuseppe Peano Giuseppe Peano (; ; 27 August 1858 – 20 April 1932) was an Italian mathematician and glottologist. The author of over 200 books and papers, he was a founder of mathematical logic and set theory, to which he contributed much notation. The st ...
(1858–1932) from 1887 until 1914. It is a simplified version of Latin, and retains its
vocabulary A vocabulary is a set of familiar words within a person's language. A vocabulary, usually developed with age, serves as a useful and fundamental tool for communication and acquiring knowledge. Acquiring an extensive vocabulary is one of the ...
. Interlingua-IL was published in the journal ''Revue de Mathématiques'' in an article of 1903 entitled ''De Latino Sine Flexione, Lingua Auxiliare Internationale'' (meaning ''On Latin Without Inflection, International Auxiliary Language''), which explained the reason for its creation. The article argued that other auxiliary languages were unnecessary, since Latin was already established as the world's international language. The article was written in classical Latin, but it gradually dropped its inflections until there were none. Language codes
ISO 639 ISO 639 is a set of standards by the International Organization for Standardization that is concerned with representation of names for languages and language groups. It was also the name of the original standard, approved in 1967 (as ''ISO 639 ...
ISO 639-2 ISO 639- 2:1998, ''Codes for the representation of names of languages — Part 2: Alpha-3 code'', is the second part of the ISO 639 standard, which lists codes for the representation of the names of languages. The three-letter codes given for e ...
and -1 were requested on 23 July 2017 at Library of Congress (proposed: ''IL'' and ''ILA''); ISO-639-3 was requested on 10 August 2017 at SIL (proposed: ''ILA'') and was rejected on 23 January 2018.


In 1903 Peano published the article ''De Latino Sine Flexione'' to introduce his language, by quoting a series of suggestions by
Leibniz Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of mat ...
about a simplified form of Latin. Peano's article appeared to be a serious development of the idea, so he gained a reputation among the movement for the auxiliary language. In 1904 Peano undertook an essay about the way to obtain the minimal grammar of an eventual minimal Latin (''Latino minimo''), with a minimal vocabulary purely international.Peano, Giuseppe (1904). ''Vocabulario de Latino internationale comparato cum Anglo, Franco, Germano, Hispano, Italo, Russo, Græco et Sanscrito'

Peano and some colleagues published articles in Latino sine flexione for several years at the ''Revue de Mathématiques''. Because of his desire to prove that this was indeed an international language, Peano boldly published the final edition of his famous
Formulario mathematico ''Formulario Mathematico'' (Latino sine flexione: ''Formulary for Mathematics'') is a book There are many editions. Here are two: * (French) Published 1901 by Gauthier-Villars, Paris. 230p.OpenLibrary OL15255022WKennedy, Hubert (2006). ''Peano. Life and Works of Giuseppe Peano''. Concord, CA: Peremptory Publications: p. 169 (''a''), p. 185 (''b''). In October 1907, Peano was at the Collège de France in
Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...
to take part in the
Delegation for the Adoption of an International Auxiliary Language The Delegation for the Adoption of an International Auxiliary Language (french: Délégation pour l'adoption d'une langue auxiliaire internationale) was a body of academics convened in the early part of the 1900s (decade) to decide on the issue of ...
. Having declared for Latino sine flexione to be adopted, he eventually could not participate in the final voting, because of labour affairs at Turin. On 26 December 1908, Peano was elected member and director of the ''Akademi internasional de lingu universal'' still using
Idiom Neutral Idiom Neutral is an international auxiliary language, published in 1902 by the International Academy of the Universal Language () under the leadership of Waldemar Rosenberger, a St. Petersburg engineer. History The Academy had its origin as ...
, which was refounded one year later under the name Academia pro Interlingua. Every academician might use their favourite form of Interlingua, the term being initially used in a general sense as a synonym for international language, yet it soon began to be specially used to denote a reformed Latino sine flexione based on the common rules the academicians were reaching by frequent votings. Thus, the name Interlingua soon began to denote the language evolving from the Academia Pro Interlingua, with the corresponding abbreviation ''IL''. However, every member was free to write in their own personal style, and indeed some members were proposing radical reforms which eventually might end up as independent languages (like Michaux's Romanal or De Wahl's
Interlingue Interlingue (; ISO 639 ''ie'', ''ile''), originally Occidental (), is an international auxiliary language created in 1922 and renamed in 1949. Its creator, Edgar de Wahl, sought to achieve maximal grammatical regularity and natural character ...
). For this reason, the name ''Peano's Interlingua'' or ''Interlingua (IL)'' might be regarded as the most accurate for the particular standard by Peano. (As found in "Interglossa and its predecessors".Hogben, Lancelot (1943). ''Interglossa. A draft of an auxiliary for a democratic world order, being an attempt to apply semantic principles to language design''

Harmondsworth, Middlesex, Eng. / New York: Penguin Books: p. 10-11. OCLC 1265553.
) The discussions to reach a standard Interlingua may be seen on the pages of ''Discussiones'', the official journal of the Academia pro Interlingua from 1909 to 1913. This and subsequent journals of the academy have been recently published in a CD-Rom by the mathematics department of the university of
Turin Turin ( , Piedmontese: ; it, Torino ) is a city and an important business and cultural centre in Northern Italy. It is the capital city of Piedmont and of the Metropolitan City of Turin, and was the first Italian capital from 1861 to 1865. Th ...
, the place where Peano developed his teaching and research. Since ''De Latino Sine Flexione'' had set the principle to take Latin nouns either in the ablative or nominative form (''nomen'' was preferred to ''nomine''), in 1909 Peano published a vocabulary in order to assist in selecting the proper form of every noun, yet an essential value of Peano's Interlingua was that the lexicon might be found straightforward in any Latin dictionary (by getting the thematic vowel of the stem from the genitive ending, that is: ''-a -o -e -u -e'' from ''-ae -i -is -us -ei''). Finally, a large vocabulary with 14 000 words was published in 1915.Peano, Giuseppe (1915). ''Vocabulario Commune ad Latino-Italiano-Français-English-Deutsch pro usu de interlinguistas'

Cavoretto - Torino.
A reformed
Interlingua Interlingua (; ISO 639 language codes ia, ina) is an international auxiliary language (IAL) developed between 1937 and 1951 by the American International Auxiliary Language Association (IALA). It ranks among the most widely used IALs and is th ...
was presented in 1951 by Alexander Gode as the last director of the International Auxiliary Language Association. It was claimed to be independent from Peano's Interlingua, because it had developed a new method to detect the ''most recent common prototypes''. But that method usually leads to the Latin ablative, so most vocabulary of Peano's Interlingua would be kept. Accordingly, the very name ''Interlingua'' was kept, yet a distinct abbreviation was adopted: ''IA'' instead of ''IL''.

Alphabet and pronunciation

According to Peano's guide to the language in 1931, "most Interlinguists are in favour of the old Latin pronunciation." This gives the pronunciation of vowels as follows: * a—as in father: * e—as in they: * i—as in feet: * o—as in tone: * u—as in rule: * y—as French u: * j—as in yes: * ae—as in eye: * oe—as in boy: Consonants are pronounced largely as in English, with the following clarifications: * b—like English b, but like p if followed by s or t: * g—like g in go, get: * h—silent in rh otherwise like English h: * qu—as qu in quarrel: * r—as in corr (trilled): * v—like English w.: * x—as ks.: * ch, ph, th—as c, p, t in can, pan, tan: * c—like k always, as in scan, scat: (not aspirated) * p—as in span * t—as in stand Not all consonants and vowels are pronounced distinctively by all people. The following variant pronunciations are allowed: * y as * ae and oe as * h silent * ch, ph, th as * ph as * v like English v, * w like English v The stress is based on the classical Latin rule: * Words with two syllables have the stress on the penult. * Words with three or more syllables have the stress on the penult only if it is heavy (closed or had a long vowel in Classical Latin), otherwise on the antepenult (p. xii). A secondary accent may be placed when necessary as the speaker deems appropriate.

Parts of speech

Though Peano removed the inflections of Latin from nouns and
adjective In linguistics, an adjective ( abbreviated ) is a word that generally modifies a noun or noun phrase or describes its referent. Its semantic role is to change information given by the noun. Traditionally, adjectives were considered one of the ma ...
s, he did not entirely remove grammatical gender, permitting the option of a
feminine Femininity (also called womanliness) is a set of attributes, behaviors, and roles generally associated with women and girls. Femininity can be understood as socially constructed, and there is also some evidence that some behaviors considered fe ...
ending for occupations. The gender of animals is immutable. All forms of nouns end with a vowel and are taken from the
ablative case In grammar, the ablative case (pronounced ; sometimes abbreviated ) is a grammatical case for nouns, pronouns, and adjectives in the grammars of various languages; it is sometimes used to express motion away from something, among other uses. ...
, but as this was not listed in most Latin dictionaries, he gave the rule for its derivation from the genitive case. The plural is not required when not necessary, such as when a number has been specified, the plural can be read from the context, and so on; however Peano gives the option of using the suffix -s to indicate it when needed. Verbs have few inflections of conjugation; tenses and moods are instead indicated by verb adjuncts. The result is a change to a positional language.


Particles that have no inflection in classical Latin are used in their natural form: * ''Supra, infra, intra, extra''... (but ''superiore, inferiore, interiore, exteriore'' from ''superior, -oris'' and so on.) * ''Super, subter, inter, praeter, semper''... (but ''nostro, vestro, dextro...'' from ''noster, -tra, -trum'' and so on.) * ''Tres, quatuor, quinque, sex, septem, octo, novem, decem''... (but ''uno'' from ''unus, -a, -um''; ''duo'' from ''duo, -ae, -o''; ''nullo'' from ''nullus, -a, -um''; ''multo'' from ''multus, -a, -um'', etc.)


The form of nouns depends on the Latin declensions. Those proper nouns written with the Roman alphabet are kept as close to the original as possible. The following are examples: München, New York, Roma, Giovanni.


* Personal * Demonstrative: ''illo'' (it, far), ''isto'' (it, near), ''ipso'' (itself); for conjunction: ''que'' (''me vide que illo es rapide'' = I see that it is fast) * Possessive: ''meo'', ''tuo'', ''suo'', ''nostro'', ''vestro'', (''suo'') * Relative and conjunctive: ''qui'' (who, that human), ''quod'' (which, that thing) * Reflexive: ''se'' * Indefinitive: ''un'', ''uno'' (''One'' tells...), ''ullo'' (any), ''omne'' or ''omni'' (all, each, every), ''aliquo'' (anyone), ''nullo'' (nothing), ''nemo'' (no one)


Verbs are formed from the Latin by dropping the final ''-re'' of the infinitive. Tense, mood, etc., are indicated by particles, auxiliary verbs, or adverbs, but none is required if the sense is clear from the context. If needed, the past may be indicated by preceding the verb with ''e'', and the future with ''i''. There are specific endings to create the
infinitive Infinitive (abbreviated ) is a linguistics term for certain verb forms existing in many languages, most often used as non-finite verbs. As with many linguistic concepts, there is not a single definition applicable to all languages. The word is d ...
participle In linguistics, a participle () (from Latin ' a "sharing, partaking") is a nonfinite verb form that has some of the characteristics and functions of both verbs and adjectives. More narrowly, ''participle'' has been defined as "a word derived fro ...
s: * Basic form: ama (loves) * Infinitive: amare (to love) * Passive participle: amato (loved) * Active participle: amante (loving)

Collateral endings

* Imperfectum (past): amaba (loved), legeba (read) * Future: amara (will/shall love), legera (will/shall read) * Conditional: amare (would love), legere (would read) The endings ''-ra'' and ''-re'' are stressed in future and conditional.

Compound tenses

Composite tenses can be expressed with auxiliary words: * Praeteritum: habe amato (have loved) * Future: debe amare / vol amare / habe ad amare (must love / will love / have to love) * Continuous tenses: me es scribente (I am writing)

Adjectives and adverbs

Adjectives are formed as follows: * If the nominative neuter ends with -e, the Latino form is unchanged. * If the nominative neuter ends with -um, the Latino form is changed to -o: novum > novo (new). * In all other cases, adjectives are formed with the ablative case from the genitive, as is the case with nouns. Adjectives can be used as adverbs if the context is clear, or ''cum mente'' or ''in modo'' can be used: * Diligente (diligent): ''Cum mente diligente'', ''cum diligente mente'', ''in modo diligente'', ''in diligente modo'' = diligently.

Comparative and superlative

* Positive: ''illo es tam habile quam te'' (it is as handy as you) * Comparative: ''illo es magis habilis quam te'' or ''illo es plus habilis quam te'' (it is handier than you) and ''illo es minus habilis quam te'' (it is less handier than you) * Superlative: ''maxim de...'' and ''minim de...''


* Bono: meliore: optimo * Malo: pejore: pessimo * Magno: majore: maximo * Parvo: minore: minimo


As with Latin, neither the definite nor the indefinite article exists in Latino sine flexione. When necessary they may be translated with pronouns or words such as ''illo'' (it, that) or ''uno'' (one): * Da ad me libro = give me (the) book * Da ad me hoc libro = give me this book * Da ad me illo libro = give me that book * Da ad me uno libro = give me a book * Da ad me illo meo libro = give me that book of mine * Da ad me uno meo libro = give me a book of mine


* Cardinals: 1 ''uno'', 2 ''duo'', 3 ''tres'', 4 ''quatuor'', 5 ''quinque'' 6 ''sex'', 7 ''septem'', 8 ''octo'', 9 ''novem'', 10 ''decem'', 20 ''viginti'', 30 ''triginta'', 40 ''quadraginta'', 50 ''quinquaginta'', 60 ''sexaginta'', 70 ''septuaginta'', 80 ''octoginta'', 90 ''nonaginta'', 100 ''centum'', 1,000 ''mille'', 1,000,000 ''millione'' * Cardinals (cont.): 11 ''decem-uno'', 12 ''decem-duo'', 19 ''decem-novem'', 21 ''viginti-uno'', 101 ''centum (et) uno'', 102 ''centum (et) duo'', 200 ''duo cento'', 300 ''tres cento'' * Ordinals: 1° ''primo'', 2° ''secundo'', 3° ''tertio'', 4° ''quarto'', 5° ''quinto'', 6° ''sexto'', 7° ''septimo'', 8° ''octavo'', 9° ''nono'', 10° ''decimo'', 20° ''vigesimo'', 30° ''trigesimo'', 40° ''quadragesimo'', 50° ''quinquagesimo'', 60° ''sexagesimo'', 70° ''septuagesimo'', 80° ''octogesimo'', 90° ''nonagesimo'', 100° ''centesimo'', 1,000° ''millesimo'', 1,000,000 ''millionesimo'' * Ordinals (cont.): 45° ''quadragesimo quinto'' or ''quadraginta quinto'', 58° ''quinquagesimo octavo'' or ''quinquaginta octavo'', 345° ''tres cento quadraginta quinto'' * Multiplicatives: ''uno vice'' (once), ''duo vice'' (twice), ''tres vice'' (three times)

Language examples


Peano formally defended the maxim that ''the best grammar is no grammar'', bearing in mind the example of Chinese. (In modern linguistics, counter to popular and Peano's usage, '' grammar'' does not refer to morphological structures alone, but also to syntax and phonology, for example, which both Latino sine flexione and Chinese still have. In this sense, "languages without grammar" cannot exist.) According to Lancelot Hogben, Peano's Interlingua still shares a major flaw with many other auxiliary languages, having "either too much grammar of the wrong sort, or not enough of the right". (p. 10) Hogben argues that at least nouns and verbs should be easily distinguished by characteristic endings, so that one can easily get an initial understanding of the sentence. Thus, in Peano's Interlingua the verbs might be given some specific, standardized verbal form, such as the
infinitive Infinitive (abbreviated ) is a linguistics term for certain verb forms existing in many languages, most often used as non-finite verbs. As with many linguistic concepts, there is not a single definition applicable to all languages. The word is d ...
, which is sufficient at the Latin
indirect speech In linguistics, indirect speech (also reported speech or indirect discourse) is a grammatical mechanism for reporting the content of another utterance without directly quoting it. For example, the English sentence ''Jill said she was coming' ...
. Instead, the raw imperative is proposed in ''De Latino Sine Flexione'': According to Hogben, another handicap is the lack of a pure article, which might clearly indicate the nouns. Nevertheless, Peano occasionally suggested that ''illo'' (that) and ''uno'' (one) might be used as articles. Once more according to Hogben, the syntax of Peano's Interlingua remained conservative: Reviewing the list of more widely known Latin titles, one might conclude that the sequence ''noun-adjective'' is the norm in Latin, yet the inverted sequence is also current."Note on Peano's Interlingua

Updated: June 2014.
The ratio is over 2 to 1 in a list of Latin titles commented by Stroh.Stroh, Wilfried (2009). ''Le latin est mort. Vive la latin!'' 007. ''Latein ist tot, es lebe Latein'' Paris: Les Belles Lettres. . E.g. "''
Principia Mathematica The ''Principia Mathematica'' (often abbreviated ''PM'') is a three-volume work on the foundations of mathematics written by mathematician–philosophers Alfred North Whitehead and Bertrand Russell and published in 1910, 1912, and 1913. ...
''". As for a sequence ''nominative-genitive'', it may be the norm in Latin in a similar ratio. E.g. "'' Systema Naturae''". Indeed, the sequence ''nominative-genitive'' must always be the norm in Peano's Interlingua, since the preposition ''de'' must introduce the genitive. Thus, ''
Philosophiæ Naturalis Principia Mathematica ( English: ''Mathematical Principles of Natural Philosophy'') often referred to as simply the (), is a book by Isaac Newton that expounds Newton's laws of motion and his law of universal gravitation. The ''Principia'' is written in Latin ...
'' would turn into ''Principio Mathematico de Philosophia Naturale''. Since the function of both the adjective and the genitive is often the same, one might infer that the sequence ''noun-adjective'' might always be the norm.

See also

Interslavic Interslavic (''Medžuslovjansky'' / ''Меджусловјанскы'') is a pan-Slavic auxiliary language. Its purpose is to facilitate communication between speakers of various Slavic languages, as well as to allow people who do not speak a S ...


External links

Instituto pro Latino sine flexione
- Site in Latino sine flexione; Peano's original writings on this language, blog in Latino sine flexione, etc.
Blog in Latino sine Flexione
* (Latino sine flexione) 100 exemplo de Interlingua, ab Giuseppe Peano * (Latino sine flexione
Revista "Discussiones", de Academia Pro Interlingua (1909-13)

Nuntios: Latino sine Flexione
in http://nuntios.blogspot.com/ {{Authority control International auxiliary languages Simplified languages Constructed languages introduced in the 1900s 1903 introductions Forms of Latin