Entry 1 sense Webster, 1913 Chieftain /chēf'-tən/ · Chief·tain · IPA /ˈt͡ʃiːf.tən/ 01 n. A captain, leader, or commander; a chief; the head of a troop, army, or clan. 1. A captain, leader, or commander; a chief; the head of a troop, army, or clan. Syn. Chief; commander; leader; head. See Chief.