"rapid oscillatory motion observed in very small particles," 1850, for Scottish scientist Dr. Robert Brown (1773-1858), who first described it.

1971, in reference to a modern spiritual movement, from new + age (n.). It had been used at various times at least since the 1840s.

"evening before the first day of the new year," c. 1300; "þer þay dronken & dalten ... on nwe gerez euen." The Julian calendar began on January 1, but the Christian Church frowned on pagan celebrations of this event and chose the Feast of the Annunciation (March 25) as its New Year's Day. The civic year in England continued to begin January 1 until late 12c., and even though legal documents then shifted to March 25, popular calendars and almanacs continued to begin on January 1. The calendar reform of 1751 restored the Julian New Year in England. New Year's was the main midwinter festival in Scotland from 17c., when Protestant authorities banned Christmas, and continued so after England reverted to Christmas, hence the Scottish flavor ("Auld Lang Syne," etc.). New Year's gathering in public places began 1878 in London, after new bells were installed in St. Paul's.

1855, from ice (n.) + age (n.). Perhaps translating German Eiszeit (1837). An earlier term in the same sense was glacial epoch (1841). Local scientific men had noticed from the late 18c. evidence that the Alpine glaciers once had been much larger; in the 1830s stray boulders, moraines, and polished bedrock in northern Europe (formerly interpreted as relics of catastrophic floods) began to be understood as revealing the former presence of a large ice cap there. When Agassiz, a convert to the theory, came to America in 1846 he found similar evidence in New England. The glacial theory and the notion that there had been several worldwide ice ages seems to have been generally accepted by the 1870s.

communist guerrilla movement and political party in Laos, 1954, from Laotian Thai, literally "Land of the Lao" (see Laos).

Latin, "anew, afresh," hence "from the beginning," from ablative of novus "new" (see new).

1794, from French ancien régime, literally "old rule," referring to the government and social order of France before the Revolution there. See ancient + regime.

"room set up for ordinary family or social use, sitting-room," 1795 (as opposed to bedroom, dining room, etc.); from living (n.) + room (n.).

Brazilian style of music, 1962, from Portuguese, literally "new tendency."

1905, from Irish, literally "we ourselves," from Old Irish féin "self," from PIE *swei-no-, suffixed form of root *s(w)e- (see idiom). The movement was founded 1905 by Irish journalist and politician Arthur Griffith (1872-1922).