Cowardly, spineless.
Without a backbone; invertebrate.
Cowardly, base.
Showing characteristics that are not manly, such as being immature, effeminate or cowardly, which might be construed as an indicator of weakness or of baseness of character.
Of or pertaining to something not human.
Not becoming of a man.
Not acceptable from a man.
In a manner that is unmanly.