quin·quen·ni·um (kwĭn-kwĕnē-əm, kwĭng-)
n. pl. quin·quen·ni·ums or quin·quen·ni·a (-kwĕnē-ə)
A period of five years.
[Latin quīnquennium : quīnque, quinque- + annus, year; see at- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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.