Dictionary

pantywaist en · ADJ

(especially, informal, not-comparable, of a male person) Weak, timid, effeminate, ineffectual.
- His rough, burly father was mortified by the lad's pantywaist behavior.

(dated, informal) An undergarment composed, in part, of panties attached to a waistband.
- Lace trimmed panty waists—50 cents. 1929 April 29, “The Altman Sale of Children's Underwear”, in The New York Times, display advertisement, page 16:
(derogatory, informal) An ineffectual, weak, or timid person, especially a boy or young man; a sissy.
- Don't be misled by the British tendency to be soft-spoken and polite. The English language didn't spread across the oceans and over the mountains and jungles and swamps because these people were pantywaists. 1943 January 24, Hal Borland, “'Baedekers' for Our Fighters: So you're going abroad, says Uncle Sam”, in The New York Times, page SM14:
- She stared at the metal bars hanging from the wood beams of the ceiling. Lined handcuffs dangled from the ends. The dungeon master would suspend his handcuffed victim from that horizontal bar. “Don’t be a pantywaist, baby. This is what you wanted.” 2010, Jasmine Haynes, “Surrender to Me”, in Hers for the Evening, New York, N.Y.: Heat/Berkley Publishing Group, →ISBN, page 271:

Spelling	Features	Labels	Source
pantywaists	Number=Plur		lexicographic