hooker (n.)

"one who or that which hooks" in any sense, agent noun from hook (v.). Meaning "prostitute" (by 1845) often is traced to the disreputable morals of the Army of the Potomac (American Civil War) under the tenure of Gen. "Fighting Joe" Hooker (early 1863), and the word might have been popularized by this association at that time (though evidence is wanting). But it is reported to have been in use in North Carolina c. 1845 ("[I]f he comes by way of Norfolk he will find any number of pretty Hookers in the Brick row not far from French's hotel. Take my advice and touch nothing in the shape of a prostitute when you come through Raleigh, for in honest truth the clap is there of luxuriant growth." letter quoted in Norman E. Eliason, "Tarheel Talk," 1956).

One early theory traces it to Corlear's Hook, a section of New York City.

HOOKER. A resident of the Hook, i.e. a strumpet, a sailor's trull. So called from the number of houses of ill-fame frequented by sailors at the Hook (i.e. Corlear's Hook) in the city of New York. [John Russell Bartlett, "Dictionary of Americanisms," 1859]

Or perhaps related to hooker "thief, pickpocket" (1560s).

But the word is likely a reference to prostitutes hooking or snaring clients. Hook in the figurative sense of "that by which anyone is attracted or caught" is recorded from early 15c.; and hook (v.) in the figurative sense of "catch hold of and draw in" is attested from 1570s; in reference to "fishing" for a husband or a wife, it was in common use from c. 1800. All of which makes the modern sense seem a natural step. Compare French accrocheuse, raccrocheuse, common slang term for "street-walker, prostitute," literally "hooker" of men.

The family name Hooker (attested from c. 975) would mean "maker of hooks," or else refer to an agricultural laborer who used a hook (compare Old English weodhoc "weed-hook").