slinky (adj.)

"sinuous and slender," of women or clothes, 1921, from slink + -y (2). Related: Slinkily; slinkiness.

Earlier usages of it meant "lank; lean; flaccid" (Century Dictionary 1895). Slinking (adj.) "moving in a slinking manner" is by 1840, and slink is attested from 1670s as an adjective, "thin, slender, lean; starved and hungry," of cattle, etc.

As a proprietary name (with capital from S-) for a coil of spring marketed as a toy, 1948, by James Industries Inc., Philadelphia, U.S.A.