n. pl. an·ni·ver·sa·ries
1. The annually recurring date of a past event, as of personal or historical importance: a wedding anniversary; the anniversary of the founding of Rome.
2. A date that follows a certain event by a specified amount of time: his six-month anniversary of quitting smoking.
3. An event at which an anniversary is celebrated.
[Middle English anniversarie, from Medieval Latin (diēs) anniversāria, anniversary (day), from Latin, feminine of anniversārius, returning yearly : annus, year; see at- in the Appendix of Indo-European roots + versus, past participle of vertere, to turn; see wer-2 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.