early 15c., "citizen of the ancient Greek city of Sparta" (q.v.), from Latin Spartanus. As an adjective from 1580s; meaning "characterized by frugality or courage" is from 1640s.
Entries linking to spartan
Sparta
capital of Laconia in ancient Greece, famed for severity of its social order, the frugality of its people, the valor of its arms, and the brevity of its speech. Also for dirty boys, men vain of their long hair, boxing girls, iron money, and insufferable black broth. The name is said to be from Greek sparte "cord made from spartos," a type of broom, from PIE *spr-to-, from root *sper- (2) "to turn, twist" (see spiral (adj.)). Perhaps the reference is to the cords laid as foundation markers for the city. Or the whole thing could be folk etymology.