Is it ensure, insure, or assure?
man's evening dress for semiformal occasions, 1889, named for Tuxedo Park, N.Y., site of a country club where it first was worn in 1886. The name is an attractive subject for elaborate speculation, e.g.:
The Wolf tribe in New York was called in scorn by other Algonquians tuksit: round foot, implying that they easily fell down in surrender. In their region thus came the names Tuxedo and Tuxedo Lake, which were acquired by the Griswold family in payment of a debt. There the family established the exclusive Tuxedo Club, and there in the late 1880s Griswold Lorillard first appeared in a dinner jacket without tails, a tuxedo. By a twist of slang, one may now refer to a man in a tuxedo as a 'wolf. [Joseph T. Shipley, "The Origins of English Words," 1984]But in another version of the story, p'tuksit was the Algonquian word for "wolf," the animal, perhaps from the shape of its paws. The authoritative Bright, however, says the tribe's name probably is originally a place name, perhaps Munsee Delaware (Algonquian) p'tuck-sepo "crooked river." Short form tux is attested from 1922.