gaff (n.1) Look up gaff at
"iron hook," c. 1300, gaffe, from Old French gaffe "boat hook" (see gaffe). Specifically of the hook on a fishing spear from 1650s. As a type of spar from 1769. Related: gaff-hook.
gaff (n.2) Look up gaff at
"talk," 1812, in phrase blow the gaff "spill a secret," of uncertain origin. OED points out Old English gafspræc "blasphemous or ribald speech," and Scottish gaff "loud, rude talk" (by 1825). Compare gaffe.
gaff (n.3) Look up gaff at
"cheap music hall or theater; place of amusement for the lowest classes," 1812, British slang, earlier "a fair" (1753), of unknown origin.