slew (n.1) Look up slew at
"swampy place," 1708, North American variant of slough.
slew (v.) Look up slew at
"to turn, swing, twist," 1834, earlier slue (1769), a nautical word, of unknown origin. Slewed (1801) is old nautical slang for "drunk." Slew-foot "clumsy person who walks with feet turned out" is from 1896.
slew (n.2) Look up slew at
"large number," 1839, from Irish sluagh "a host, crowd, multitude," from Celtic and Balto-Slavic *sloug- "help, service" (see slogan).