The "prostitute" sense is the subject of a folk etymology connecting it to US Civil War general General Hooker, but the earliest known use dates to 1835. More plausibly, it has also been connected to coastal features called Hook in the ports of New York and Baltimore. Careful learned inference is not conclusive. See this essay, pp 105ff.
1914, Edgar Rice Burrows, The Mucker Chapter , … for there was scarce one of us that thought the old hooker would weather so long and hard a blow. We were mighty fortunate to come through it so handily.
(rugby) A player who hooks the ball out of the scrum with his foot.
2011, September 18, Ben Dirs, Rugby World Cup 2011: England 41-10 Georgia, Hooker Dylan Hartley was sent to the sin-bin after yet another infringement at the breakdown and, on the stroke of half-time, Georgia's territorial advantage finally told when number eight Basilaia surged over from the base of the scrum for a try next to the posts.
(slang, dated) A measurement of alcohol without definite amounts, meaning the same thing as a "slug" (of gin), an overlarge gulp. Used from the 1920s through the 1940s.
