step-in

From step + in.

step-in (plural step-ins)

1. (also in plural) An item of clothing which one steps into to put on; specifically, women's panties.
   • 1931, William Faulkner, Sanctuary, Vintage, published 1993, page 46:

     ‘Doc got that step-in in Memphis,’ the third said. ‘Off a damn whore.’

   • 1934, F[rancis] Scott Fitzgerald, Tender is the Night: A Romance, New York, N.Y.: Charles Scribner’s Sons, →OCLC; republished as chapter VII, in Malcolm Cowley, editor, Tender is the Night: A Romance [...] With the Author’s Final Revisions, New York, N.Y.: Charles Scribner’s Sons, 1951, →OCLC, book V (The Way Home: 1929–1930), page 315:

     One of the girls hoisted her skirt suddenly, pulled and ripped at her pink step-ins and tore them to a sizeable flag; then, screaming "Ben! Ben!" she waved it wildly.

• T-spine, in step, instep, nepits, pinest, septin, spinet