(formerly, in India) a native soldier, usually an infantryman, in the service of Europeans, esp. of the British.
Origin: 1675–85, in sense “horseman”; 1710–20 for current sense; var. of sipahi < Urdu < Pers sipāhī horseman, soldier, deriv. of sipāh army; cf. spahi
"native of India in British military service," 1717, from Port. sipae, from Urdu sipahi, from Pers. sipahi "soldier, horseman," from sipah "army." The Sepoy Mutiny was 1857-8.