slew (n.1)
"swampy place," 1708, North American variant of slough.
slew (v.)
"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)
"large number," 1839, from Irish sluagh "a host, crowd, multitude," from Celtic and Balto-Slavic *sloug- "help, service" (see slogan).