Semantic relation of sameness or (strong) similarity in meaning of two or more linguistic expressions. In lexicology, grammar, or stylistics it is a term whose interpretations are as varied as the semantic theories in which it is found. The following distinctions are generally made. (a) Complete (absolute, strict, or pure) synonymy: by definition, complete synonymy presupposes the unconditional substitutability of the given expressions in all contexts and refers both to denotative (denotatum) and to connotative (connotation) semantic elements. In the narrow interpretation of this operational definition and in its restriction to a specific linguistic system, it appears that the concept of linguistic economy eliminates, in almost all cases, the possibility of complete synonymy at least in lexemes. (b) Partial synonymy, which refers either to lexemes which can be substituted in some but not all contexts depending on their denotative and connotative meaning (get/receive a letter, but not *receive a cold) or to lexemes with the same denotative meaning that have different connotations depending on regional (peanuts vs goobers), socio-dialectal (money, dough, bread, moolah), political (team, committee), stylistic (room, suite), or sublinguistic (sublanguage)(salt, NaCl) distinctions. The causes of synonymic variation may be traced especially to the fact that the vocabulary of a language is an open system which can rapidly adapt to dialectal, social, and scientific developments. Synonymy comes about through the concurrent development of dialectal and standard, colloquial, and technical variants, through euphemistic tendencies towards circumlocution (e.g. die vs pass away), through language manipulation (e.g. free world vs the West) and through the adoption of foreign words (e.g. following vs entourage). The following constitute operational processes for determining the degree of lexical synonymy: the substitution test, which determines the substitutability of synonymous lexemes in sentences of identical syntactic structure; distribution analysis. which establishes the distributional limits in particular contexts; and componential analysis, which provides descriptions via identical bundles of semantic features. Even greater exactness in describing the denotative aspect of synonymy is achieved through the definition in formal logic according to which synonymy corresponds to an equivalence relation: Two expressions E1 and E2 in the same syntactic position are synonymous if E1 implies E2 and E2 implies E1. In addition, the distinction between extension and intension makes it possible to differentiate more precisely referential synonymy from sameness of sense. For example, the expressions morning star and evening star are, to be sure, extensionally equivalent (i.e.
