adjective

no longer alive.

a dead body

deceased,expired,departed,gone,no more,passed on,passed away,late,lost,lamented,perished,fallen,slain,slaughtered,killed,murdered,lifeless,not breathing,having breathed one’s last,defunct,extinct,inanimate,insentient,insensate,inert,(as) dead as a doornail,six feet under,pushing up daisies,under the sod,with God,asleep,at peace,demised,exanimate

adverb

absolutely; completely.

you’re dead right

completely,absolutely,totally,utterly,deadly,perfectly,entirely,wholly,fully,quite,thoroughly,unreservedly,definitely,certainly,positively,unconditionally,categorically,unquestionably,no doubt,undoubtedly,without a doubt,without question,surely,unequivocally,exactly,precisely,decisively,conclusively,manifestly,in every way,in every respect,one hundred per cent,every inch,to the hilt