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.
1382, "harmful, noxious," from noye "harm, misfortune," shortened form of anoi "annoyance" (from O.Fr. anoier, see annoy) + -some. Meaning "bad-smelling" first recorded 1577.