1. Not possessing qualities befitting a man
   "His unmanly behaviour during the crisis disappointed his colleagues";
   - 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
   "He unmanly cowered in the face of danger";
   - unmanfully

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