1610s, from Dutch Sennecas, collective name for the Iroquois tribes of what became upper New York, of uncertain origin, perhaps from a Mahican name for the Oneida or their village. Earlier sinnekens, senakees; the form of the English word probably was influenced by the name of the ancient Roman philosopher. The name sometimes was used by Americans for all the Iroquois.
central American republic, named for the region, visited 1522 by Spanish conquistador Gil González Dávila, who is said to have named it for a local native chieftain, Nicarao, with Spanish agua "water." Related: Nicaraguan.
casual, generic term of address for a man, 1928, from Irish and Gaelic mac, a common element in Scottish and Irish names (literally "son of;" see Mac-); hence used generally from 1650s for "a Celtic Irishman."