Meaning of “dead” - Learner’s Dictionary

dead

adverb uk us /ded/

informal extremely or completely:

UK The exam was dead easy.
US His advice was dead wrong.
be dead set against sth/doing sth

to oppose something strongly:

My parents were dead set against us getting married.
stop dead

to suddenly stop moving or doing something

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