Similarity may refer to:

In mathematics and computing

Similarity (geometry) In Euclidean geometry, two objects are similar if they have the same shape, or one has the same shape as the mirror image of the other. More precisely, one can be obtained from the other by uniformly scaling (enlarging or reducing), possibly w ...

, the property of sharing the same shape *

Matrix similarity In linear algebra, two ''n''-by-''n'' matrices and are called similar if there exists an invertible ''n''-by-''n'' matrix such that B = P^ A P . Similar matrices represent the same linear map under two (possibly) different bases, with being ...

, a relation between matrices *

Similarity measure In statistics and related fields, a similarity measure or similarity function or similarity metric is a real-valued function that quantifies the similarity between two objects. Although no single definition of a similarity exists, usually such meas ...

, a function that quantifies the similarity of two objects **

Cosine similarity In data analysis, cosine similarity is a measure of similarity between two sequences of numbers. For defining it, the sequences are viewed as vectors in an inner product space, and the cosine similarity is defined as the cosine of the angle betw ...

, which uses the angle between vectors **

String metric In mathematics and computer science, a string metric (also known as a string similarity metric or string distance function) is a metric that measures distance ("inverse similarity") between two text strings for approximate string matching or comp ...

, also called string similarity **

Semantic similarity Semantic similarity is a metric defined over a set of documents or terms, where the idea of distance between items is based on the likeness of their meaning or semantic content as opposed to lexicographical similarity. These are mathematical tool ...

, in computational linguistics

In linguistics

Lexical similarity In linguistics, lexical similarity is a measure of the degree to which the word sets of two given languages are similar. A lexical similarity of 1 (or 100%) would mean a total overlap between vocabularies, whereas 0 means there are no common words. ...

In other fields

Similitude (model) Similitude is a concept applicable to the testing of engineering models. A model is said to have similitude with the real application if the two share geometric similarity, kinematic Kinematics is a subfield of physics, developed in classica ...

, in engineering, describing the geometric, kinematic and dynamic 'likeness' of two or more systems *

Similarity (psychology) Similarity refers to the psychological degree of identity of two mental representations. It is fundamental to human cognition since it provides the basis for categorization of entities into kinds and for various other cognitive processes. It underwr ...

Similarity (philosophy) In philosophy, similarity or resemblance is a relation between objects that constitutes how much these objects are alike. Similarity comes in degrees: e.g. oranges are more similar to apples than to the moon. It is traditionally seen as an interna ...

Musical similarity The notion of musical similarity is particularly complex because there are numerous dimensions of similarity. If similarity takes place between different fragments from one musical piece, a musical similarity implies a repetition of the first occurr ...

Chemical similarity Chemical similarity (or molecular similarity) refers to the similarity of chemical elements, molecules or chemical compounds with respect to either structural or functional qualities, i.e. the effect that the chemical compound has on reaction partn ...

Similarity (network science) Similarity in network analysis occurs when two nodes (or other more elaborate structures) fall in the same equivalence class. There are three fundamental approaches to constructing measures of network similarity: structural equivalence, automor ...

* Structural similarity * ''Similar'' (film), an upcoming South Korean film

In mathematics and computing

In linguistics

In other fields

See also