adj. 25B6; adjective
a decrepit old man : FEEBLE, infirm, weak, weakly, frail; disabled, incapacitated, crippled, doddering, tottering; old, elderly, aged, ancient, senile; informal past it, over the hill, no spring chicken.
a decrepit house : DILAPIDATED, rickety, run down, tumbledown, ramshackle, derelict, ruined, in (a state of) disrepair, gone to rack and ruin; battered, decayed, crumbling, deteriorating.
strong, sound.