from The American Heritage® Dictionary of the English Language, 4th Edition
- n.pl. The 15th day of March, May, July, or October or the 13th day of the other months in the ancient Roman calendar.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. In the Roman calendar the fifteenth day of March, May, July, October, and the thirteenth day of the other months. Eight days after the nones.
- n. Plural form of ide.
from the GNU version of the Collaborative International Dictionary of English
- n.pl. The fifteenth day of March, May, July, and October, and the thirteenth day of the other months.
from The Century Dictionary and Cyclopedia
- In the ancient Roman calendar, the eighth day after the nones —that is, the 13th of January, February, April, June, August, September, November, and December, and the 15th of March, May, July, and October.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. in the Roman calendar: the 15th of March or May or July or October or the 13th of any other month
Middle English, from Old French, from Latin Īdūs.(American Heritage® Dictionary of the English Language, Fourth Edition)
from Latin idus, possibly from Latin iduare to divide (Wiktionary)
from ide a fish (Wiktionary)