'Dead' is a frozen past participle meaning 'having died' — yet 'die' itself is a Viking loanword.
No longer alive; having ceased to live; lacking sensation, activity, or force; complete or absolute.
From Old English 'dēad,' from Proto-Germanic *daudaz, a past-participial adjective from the PIE root *dʰew- (to die, to become senseless). The word is literally 'having died' — a frozen past participle that became an adjective. The same PIE root produced the noun 'death' (Old English dēaþ) and, through Old Norse, the verb 'die' (Old Norse deyja). Old English formed 'dead' natively but borrowed