originally (c.1500) a verb, "to push, thrust," of unknown origin. Meaning "raise or bend into a hump" is 1670s. Perhaps a variant of bunch. The noun is attested from 1620s, originally "a push, thrust." Figurative sense of "hint, tip" (a "push" toward a solution or answer), first recorded 1849, led to that of "premonition, presentiment" (1904).
: This was too good a hunch play to let drop
An intuitive premonition; a shrewd idea or notion: I gotta hunch she won't come back
: As I hunch it, the answer is triple
[1904+; said to be fr a gamblers' belief that touching a hunchback's hump would bring good luck]