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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.