All 12 months have at least 28 days. February is the only month that has exactly 28 days in common years, and 29 days in leap years.
3 There is a difference between a duration period of three months as in "trimester" and an event occurring every 3 months as in "quarterly". In the same vein you would have a quadrimester or tri-annually (which means three times a year; not every 3 months) both being correct in the right context.
Is there a proper term to describe ⅓ of a year (4 months)?
What months are quarterly? Quarterly months are months that fall on 1/4th of every year. The quarterly months are January-March, April-June, July-September, and October-December.
One year of a lunar calendar has 12 months, but it's about 11 days shorter than one year of the Gregorian calendar. A lunisolar calendar has months that are based on the cycle of the moon phases ...