calends

noun[plural only]6

1. •
   Often with initial capital: the first day of a month.

   • The third day before the calends of February is 30 January, the third calends of March is 27 or 28 February, and the third of the calends of May is 29 April.
2. •
   (historical) The first day of a month of the Roman calendar.
3. •
   A day for settling debts and other accounts.
4. •
   (rare) Synonym of calendar; (figurative) an account, a record.

   • [N]ow doth [John] Oldcastle shine: / Him for a Saint within your Kalends hold. — 1601
5. •
   (figurative, no longer used) The first day of something; a beginning.

   • Whoever shall sell a calf or a yearling, let him be answerable against the scab from the calends of winter until the Feast of Patrick. — 1909
6. •
   (Judaism, no longer used) Synonym of Rosh Hodesh (“the Jewish festival of the new moon, which begins the months of the Hebrew calendar”).

   • חֹדֶשׁ m. […] the new moon, the day of the new moon, the calends of a lunar month which was a festival of the ancient Hebrews, Num[bers] 29:6; 1 Sam[uel] 20:5; 18:24; Ex[odus] 19:1, […] — 1846