synonymy

n. quality of being similar in meaning; study of synonyms; list of words with similar or related meanings; list of scientific names belonging to a species and its subdivisions (Biology)

In scientific nomenclature, synonyms are different scientific names used for a single taxon. Usage and terminology are different for zoology and botany.
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Noun
1. the semantic relation that holds between two words that can (in a given context) express the same meaning
(synonym) synonymity, synonymousness
(hypernym) semantic relation

(n.)
The quality of being synonymous; sameness of meaning.
  

(n.)
A system of synonyms.
  

(n.)
A figure by which synonymous words are used to amplify a discourse.
  

Synonyms and related words:
agreement, biographical dictionary, chemical dictionary, coequality, coincidence, congruence, correspondence, desk dictionary, dialect dictionary, dictionary, dictionary of quotations, electronics dictionary, equality, equivalence, etymological dictionary, foreign-language dictionary, gazetteer, general dictionary, geological dictionary, gloss, glossary, gradus, homogeneity, homoousia, identity, indistinguishability, lexicon, no difference, nomenclator, oneness, onomasticon, phrase book, polyglot dictionary, rhyming dictionary, sameness, science dictionary, self-identity, selfhood, selfness, selfsameness, slang dictionary, specialized dictionary, synonym dictionary, synonymity, synonymousness, thesaurus, treasury of words, unabridged dictionary, unity, vocabulary, wordbook|