Meaning of “stun” - Learner’s Dictionary

stun

verb [ T ] uk us /stʌn/ (present participle stunning, past tense and past participle stunned)
SHOCK

to shock or surprise someone very much:

[ often passive ] Friends and family were stunned by her sudden death.
MAKE UNCONSCIOUS

to make a person or animal unconscious, usually by hitting them on the head

(Definition of “stun” from the Cambridge Learner’s Dictionary © Cambridge University Press)