(1):
(n.) The quadrennial celebration of the modern Olympic games; as, the first Olympiad (1906).
(2):
(n.) A period of four years, by which the ancient Greeks reckoned time, being the interval from one celebration of the Olympic games to another, beginning with the victory of Cor/bus in the foot race, which took place in the year 776 b.c.; as, the era of the olympiads.