Meaning

verb break down

noun a state of decay usually accompanied by an offensive odor

noun (biology) the process of decay caused by bacterial or fungal action

originInherited from Middle English roten, rotten, from Old English rotian (“to rot, become corrupted, ulcerate, putrefy”), from Proto-West Germanic *rotēn, from Proto-Germanic *rutāną (“to rot”).

Etymology from Wiktionary, CC BY-SA 3.0