WordWeb Online

1. Not possessing qualities befitting a man
   - unmanful, unmanlike
    
2. Lacking in courage and manly strength and resolution; contemptibly fearful
   "He despised himself for entertaining such unmanly considerations";
   - pusillanimous, poor-spirited

1. Without qualities thought to befit a man
   - unmanfully

See also: camp, cissy [Brit], cowardly, effeminate, emasculate, epicene, fearful, sissified, sissy, sissyish, womanish

Antonym: manly