adjective

rotting or decomposing through the action of bacteria and fungi.

the odour of decaying fish

decomposing,decomposed,rotting,rotten,putrescent,putrid,bad,off,spoiled,spoilt,perished,mouldy,mouldering,festering,fetid,stinking,smelly,rancid,rank,maggoty,worm-eaten,wormy,flyblown