Olympiad (n.)youdaoicibaDictYouDict[Olympiad 词源字典]
late 14c., "period of four years" (between Olympic games), from Old French olimpiade "period of four years," from Latin Olympiadem, from Greek olympiados, genitive of Olympias (see Olympic). Used by ancient Greeks as a unit in computing time. Revived in modern usage with revival of the games, 1896.[Olympiad etymology, Olympiad origin, 英语词源]
Olympian (adj.)youdaoicibaDictYouDict
"of or belonging to Olympus," c. 1600; see Olympic + -ian. The noun meaning "a great god of ancient Greece" is attested from 1843, from Late Latin Olympianus, from Greek Olympios "pertaining to Olympus;" sense of "one who competes in the (modern) Olympic Games" is from 1976.