Offensive to the point of arousing disgust; foul: a noisome odor.
Harmful or dangerous: noisome fumes.
[Middle English noiesom : noie, harm (short for anoi, annoyance, from Old French, from anoier, to annoy; see annoy) + -som, adj. suff.; see -some1.] noi'some·ly adv., noi'some·ness n.