1590s, "to deprive of the attributes of a human being," from un- (2) + verbal derivative of man (n.). Meaning "to deprive of manly courage" is attested from c. 1600; that of "to emasculate" is from 1680s.
an unmanning experience
unlovely
unlucky
unmade
unmake
unmaking
unman
unmanageable
unmanaged
unmanly
unmanned
unmannerly