(informal, dated, especially of a male person) Weak, timid, effeminate, ineffectual.His rough, burly father was mortified by the lad's pantywaist behavior.
1929 April 29, "The Altman Sale of Children's Underwear" (display advertisement), The New York Times, p. 16:Lace trimmed panty waists—50 cents.
(pejorative, dated) An ineffectual, weak, or timid person, especially a boy or youngman; a sissy.
1943 Jan. 24, Hal Borland, "'Baedekers' for Our Fighters: So you're going abroad, says Uncle Sam," The New York Times, p. SM14: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.