Old English hoc "hook, angle," perhaps related to Old English haca "bolt," from Proto-Germanic *hokaz/*hakan- (cf. Old Frisian hok, Middle Dutch hoek, Dutch haak, German Haken "hook"), from PIE *keg- "hook, tooth" (cf. Russian kogot "claw"). For spelling, see hood (n.1).
Boxing sense of "short, swinging blow with the elbow bent" is from 1898. Figurative sense was in Middle English (see hooker). By hook or by crook (late 14c.) probably alludes to tools of professional thieves. Hook, line, and sinker "completely" is 1838, a metaphor from angling.
To be dismissed, silenced, or rejected, esp suddenly: Just when he thought he was doing so well, he got the hook
[1940s+ Show business; fr the notion that a wretched performer, esp at an amateur night, was pulled forcibly off the stage with a hook]