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.
the GNU version of the Collaborative International Dictionary of English
noun-plural. The fifteenth day of March, May, July, and October, and the thirteenth day of the other months.
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.
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
Word Usage
"We all suffer from NIH (Not Invented Here) syndrome, our natural reaction to someone else's ides is "why it won't work" vs. "let's give it a try!""