synonymy

Synonymy is a semantic relation between words that have overlapping meanings. The term comes from the Greek syn- meaning together and onoma meaning name. In general use, synonyms are words that can be substituted for one another in at least some contexts without a major change in meaning. In strict terms, complete synonymy—interchangeability in all contexts—is rare.

Near-synonyms are common: two words share substantial overlap but differ in nuance, formality, or collocation. Examples include begin and start, sofa and couch, and automobile and car. The choice among them depends on context, speaker, and regional preferences. Context can alter whether two words are truly interchangeable.

Several factors shape synonymy. Connotation, tone, and register matter: a word may be a synonym in one sense but carry different evaluative or stylistic overtones. Polysemy can complicate substitution, since different senses of a word may have different set of synonyms. Additionally, synonyms are often asymmetrical and context-dependent; one term may be interchangeable in one domain but not in another.

In lexicography and natural language processing, synonymy is modeled as links between sense inventories or as synonym sets. Challenges include handling polysemy and homonymy, capturing subtle differences in frequency and collocation, and recognizing domain-specific synonyms. Ultimately, true synonymy is a nuanced and context-sensitive phenomenon rather than a simple one-to-one equivalence.

See also: lexical semantics, polysemy, antonymy, hypernymy, word sense.