Pronunciation: (īdz), [key]
—n. (used with a sing. or pl. v.)
(in the ancient Roman calendar) the fifteenth day of March, May, July, or October, and the thirteenth day of the other months.
a Greek plural suffix appearing in scientific names: cantharides.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.