A feminine, limp-wristed guy who lacks courage. May or may not be gay, but is usually assumed to be.
"Jimmy swears that he likes chicks, even though he's such an obvious pantywaist."
1) For a small child, undershirt and underpants which button together at the waist.
2) An effeminate man, derogatory.
1) My kid is dressed in a pantywaist, dress and mary-Janes.
2) That wus is an obvious pantywaist.