month

Etymology

From Middle English month, moneth, from Old English mōnaþ (“month”), from Proto-Germanic *mēnōþs (“month”), from Proto-Indo-European *mḗh₁n̥s (“moon, month”), probably from Proto-Indo-European *meh₁- (“to measure”), referring to the moon's phases as the measure of time, equivalent to moon + -th. Cognate with Scots moneth (“month”); North Frisian muunt (“month”); Saterland Frisian Mound (“month”), Dutch maand (“month”); German Low German Maand, Monat (“month”); German Monat (“month”); Danish and Norwegian Bokmål måned (“month”); Norwegian Nynorsk and Swedish månad (“month”); Icelandic mánuði (“month”); Latin mēnsis (“month”); Ancient Greek μήν (mḗn); Armenian ամիս (amis); Old Irish mí; Old Church Slavonic мѣсѧць (měsęcĭ). See also moon.

noun

1. A period into which a year is divided, historically based on the phases of the moon.
   July is my favourite month.
   Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too. GDP measures the total value of output in an economic territory. Its apparent simplicity explains why it is scrutinised down to tenths of a percentage point every month. 2013-08-03, “Boundary problems”, in The Economist, volume 408, number 8847
2. A period of 30 days, 31 days, or some alternation thereof.
   We went on holiday for two months.
   Charles had not been employed above six months at Darracott Place, but he was not such a whopstraw as to make the least noise in the performance of his duties when his lordship was out of humour. 1959, Georgette Heyer, chapter 1, in The Unknown Ajax
   With the north London derby to come at the weekend, Spurs boss Harry Redknapp opted to rest many of his key players, although he brought back Aaron Lennon after a month out through injury. September 29, 2011, Jon Smith, “Tottenham 3-1 Shamrock Rovers”, in BBC Sport
3. (obsolete, in the plural) A woman's period; menstrual discharge.