noun
Usage: usually capitalized G
Etymology: Gregorian (I)
: a revision of the Julian calendar introduced in 1582 and adopted in Great Britain and the English colonies in America in 1752 involving the suppression of the 10 days, or after 1700 11 days, by which the vernal equinox had become displaced and providing that only those centesimal years divisible by 400 should be leap years — see month table