unnerve
un.nerve \.*n-'n*rv, '*n-\ vt 1: to deprive of courage, strength, or steadiness 2: to cause to become nervous : UPSET deprive of vigor. 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 SYN syn UNNERVE, ENERVATE, UNMAN, EMASCULATE mean to
Webster's English Dictionary