anorak n.

Eskimo's waterproof, hooded jacket, 1924, from Greenland Eskimo anoraq. Applied to Western imitations of this garment from 1930s. In British slang, "socially inept person" (Partridge associates it with a fondness for left-wing politics and pirate radio), by 1983, on the notion that that sort of person typically wears this sort of coat.