Gregorian calendar, New Style calendar - the solar calendar now in general use, introduced by Gregory XIII in 1582 to correct an error in the Julian calendar by suppressing 10 days, making Oct 5 be called Oct 15, and providing that only centenary years divisible by 400 should be leap years; it was adopted by Great Britain and the American colonies in 1752

First of May, May 1, May Day - observed in the United States to celebrate the coming of spring; observed in Russia in honor of labor

Mother's Day - second Sunday in May

Armed Forces Day - the 3rd Saturday in May

Decoration Day, Memorial Day - U.S., last Monday in May; commemorates the members of the United States armed forces who were killed in war

Commonwealth Day, Empire day, May 24 - British, anniversary of Queen Victoria's birth

Gregorian calendar month - a month in the Gregorian calendar

mid-May - the middle part of May

spring, springtime - the season of growth; "the emerging buds were a sure sign of spring"; "he will hold office until the spring of next year"

Crataegus, genus Crataegus - thorny shrubs and small trees: hawthorn; thorn; thorn apple

haw, hawthorn - a spring-flowering shrub or small tree of the genus Crataegus