The Collaborative International Dictionary of English v.0.48:
pantywaist \pantywaist\ n. A timid man or boy considered childish or unassertive. Syn: sissy, pansy, milksop, Milquetoast. [WordNet 1.5]WordNet (r) 3.0 (2006):
pantywaist n 1: a timid man or boy considered childish or unassertive [syn: sissy, pantywaist, pansy, milksop, Milquetoast]