Definition of: synonymy

(si·non′ə·mē) noun plural ·mies
1. The quality of being synonymous; the expressing or extending of an idea by the use of synonyms.
2. The science or systematic collection and study of synonyms; the use and nice discrimination of synonyms: also syn·o·nym·ics (sin′ə·nim′iks).
3. A book treating of or discriminating the meaning of synonyms or of allied terms.
4. An index, list, or collection of synonyms, as in scientific nomenclature. [<LL synonymia <Gk. synōnymia <synōnymos. See SYNONYM.]