(1)   A time unit of approximately 30 days
"He was given a month to pay the bill"
(2)   One of the twelve divisions of the calendar year
"He paid the bill last month"


Middle English < Old English mōnað < Proto-Germanic *mēnōþ- < Proto-Indo-European *me(n)ses- (moon, month), probably from PIE base *mê- (to measure), referring to the moon’s phases as the measure of time. Cognate with moon.
  • Cognates include: Ancient Greek: μήν (mḗn), Armenian: ամիս (amis), German: Monat, Old High German: mānōd, Middle High German: mānōt, Old Irish: , and Old Slavic: (měsęncĭ).


  1. A period into which a year is divided, historically based on the phases of the moon. In the Gregorian calendar there are twelve months: January, February, March, April, May, June, July, August, September, October, November and December.
  2. A period of 30 days, 31 days, or some alternation thereof.
  3. A woman's period; menstrual discharge.
    • 1621, Robert Burton, The Anatomy of Melancholy, vol. I, New York 2001, p. 234:
      Sckenkius hath two other instances of two melancholy and mad women, so caused from the suppression of their months.