A left hook was a type of left-handed boxing maneuver.
In 2366, while the crew of USS Enterprise-D was affected by Sarek's Bendii Syndrome-induced emotional outbursts, Geordi La Forge suffered a left hook to the chin. (TNG: "Sarek")
In 2374, The Doctor explained that when he lost his patience, his response usually took the form of "a devastating quip rather than a left hook". (VOY: "Retrospect")
In 2376, after being socked by someone, Harry Kim replied to Tom Paris's suggestion that it was Mossie Donegan's talking pig, saying "If it was, he had one hell of a left hook." (VOY: "Fair Haven")
In 3191, Moll claimed to have met Bolians with meaner left hooks than L'ak's. (DIS: "Mirrors")