Englishaback
adverb
□ take someone aback
Joanna was taken aback by the violence of his reaction:
surprise, shock, stun, stagger, astound, astonish, startle, take by surprise;
dumbfound, daze, nonplus, stop someone in their tracks, stupefy, take someone's breath away;
shake (up), jolt, throw, unnerve, disconcert, disturb, disquiet, unsettle, discompose, bewilder;
informal flabbergast, knock for six, knock sideways, knock out, floor, strike dumb.