"to creep, crawl" (of reptiles), from P.Gmc. *slenkanan
(cf. Swed. slinka
"to glide," Du. slinken
"to shrink, shrivel;" related to sling
(v.)). Of persons, attested from late 14c. Slinky
(adj.) "sinuous and slender," of women or clothes, first attested 1921. As a proprietary name for a spring marketed as a toy, 1948, by James Industries Inc., Philadelphia, U.S.A.