1560s, "to leap up;" 1590s, "to rejoice, triumph," from French exulter, from Latin exultare/exsultare "rejoice exceedingly, revel, vaunt, boast;" literally "leap about, leap up," frequentative of exsilire "to leap up," from ex "out" (see ex-) + salire "to leap" (see salient (adj.)). The notion is of leaping or dancing for joy. Related: Exulted; exulting.
late 14c., "tendency to change, inconstancy," from Old French mutabilité, from Latin mutabilitas, from mutabilis "changeable" (see mutable).
It is the same!—For, be it joy or sorrow,
The path of its departure still is free;
Man's yesterday may ne'er be like his morrow;
Nought may endure but Mutability.
[Shelley, from "Mutability," 1816]
"a revolving machine consisting of wooden horses or seats mounted on a circular platform," 1729, from merry (adj.) + go-round. Figurative use by 1838. Merry-totter (mid-15c.) was a Middle English name for a swing or see-saw. Also compare merry-go-down "strong ale" (c. 1500); merry-go-sorry "a mix of joy and sorrow" (1590s).
c. 1200, from Old English gamen "joy, fun; game, amusement," common Germanic (cognates: Old Frisian game "joy, glee," Old Norse gaman "game, sport; pleasure, amusement," Old Saxon gaman, Old High German gaman "sport, merriment," Danish gamen, Swedish gamman "merriment"), said to be identical with Gothic gaman "participation, communion," from Proto-Germanic *ga- collective prefix + *mann "person," giving a sense of "people together."
The -en was lost perhaps through being mistaken for a suffix. Meaning "contest for success or superiority played according to rules" is first attested c. 1200 (of athletic contests, chess, backgammon). Especially "the sport of hunting, fishing, hawking, or fowling" (c. 1300), thus "wild animals caught for sport" (c. 1300), which is the game in fair game (see under fair (adj.)), also gamey. Meaning "number of points required to win a game" is from 1830. Game plan is 1941, from U.S. football; game show first attested 1961.
c. 1300, "to strike with a quick, sharp motion, to slap," from Old English clæppan "to throb, beat," or from or influenced by its Old Norse cognate, klappa, a common Germanic echoic verb (compare Old Frisian klapa "to beat," Old High German klaphon, German klappen, Old Saxon klapunga).
Meaning "to make a sharp noise" is late 14c. Of hands, "to beat together to get attention or express joy," from late 14c. Without specific mention of hands, "to applaud, to manifest approbation by striking the hands together," 1610s. To clap (someone) on the back is from 1520s and retains the older sense. Related: Clapped; clapping.