period, period of time, time period - an amount of time; "a time period of 30 years"; "hastened the period of time of his recovery"; "Picasso's blue period"

millennium - a span of 1000 years

decade, decennary, decennium - a period of 10 years

quattrocento - the 15th century in Italian art and literature

half-century - 50 years

quarter-century - 25 years

large integer - an integer equal to or greater than ten