ides

 
Pronunciation: /ʌɪdz/

plural noun

  • (in the ancient Roman calendar) a day falling roughly in the middle of each month (the 15th day of March, May, July, and October, and the 13th of other months) from which other dates were calculated. Compare with nones, calends.

Origin:

late Old English: from Old French, from Latin idus (plural), of unknown origin