unnerve, enervate, unman, emasculate mean to deprive of strength or vigor and the capacity for effective action.

unnerve implies marked often temporary loss of courage, self-control, or power to act.

enervate suggests a gradual physical or moral weakening (as through luxury or indolence) until one is too feeble to make an effort.

unman implies a loss of manly vigor, fortitude, or spirit.

emasculate stresses a depriving of characteristic force by removing something essential.