syn·on·y·mous 
(sĭ-nŏnə-məs)
(sĭ-nŏnə-məs)adj.
1. Having the character of a synonym: synonymous words; synonymous species.
2. Equivalent in connotation: "a widespread impression that ... Hollywood was synonymous with immorality" (Doris Kearns Goodwin).
[From Medieval Latin synōnymus, from Greek sunōnumos : sun-, syn- + onoma, onuma, name; see n-men- in the Appendix of Indo-European roots.]
syn·ony·mous·ly adv.