"raise or bend into a hump," 1650s; earlier "to push, thrust" (c. 1500), of unknown origin. Perhaps a variant of bunch (v.). Related: Hunched; hunching.
1620s, "a push, thrust," from hunch (v.) in its older sense. Figurative sense of "a hint, a tip" (a "push" toward a solution or answer), first recorded 1849, led to that of "premonition, presentiment" (1904).