month / mən[unvoicedth]/ • n. (also calendar month) each of the twelve named periods into which a year is divided: the first six months of 1992 | it was the end of the month. ∎  a period of time between the same dates in successive calendar months: the president's rule was extended for six more months from March 3. ∎  a period of 28 days or four weeks: the fourth month of pregnancy. ∎  a lunar month.PHRASES: a month of Sundays inf. a very long, seemingly endless period of time: no one will find them in a month of Sundays.

month recorded from Old English (in form mōnaþ), and of Germanic origin, the word is related to moon, and the primitive calendar month of many early civilizations began on, or on the day after, the day of the full moon.
a month of Sundays a very long period of time.
month's mind in the Christian Church, the commemoration of a dead person by the celebration of a requiem mass or (later more widely) special prayers on the day one month after the date of the death or funeral.

See also labours of the month at labour.

month OE. mōnað = OS. mānoth (Du. maand), OHG. mānōd (G. monat), ON. mánuðr, Goth. mēnōþs :- Gmc. *mænōþ(āz); cf. MOON.
Hence monthly adj. and adv. XVI; see -LY1, -LY2.

month Time taken for the Moon to travel completely around the Earth. The sidereal month is the time of one revolution with respect to the stars, and is equal to 27.32 days. As the Earth is in motion around the Sun, the synodic month – from full moon to full moon – is longer (29.53 days) than the sidereal month.