1. Offensive to the point of arousing disgust; foul: a noisome odor.
2. 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.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.