(pl.) c.1330, "middle day of a Roman month," from Fr. Ides (12c.), from L. idus "the eighth day after nones," a word perhaps of Etruscan origin. The 15th of March, May, July, and October; the 13th of other months.
Since it's mid-March, I was going to talk about Midmarch, but it's down at the moment, so we'll pretend it doesn't exist. Instead, play Night Fantastic!