pungent
Meaning: having a pointed, sharp quality—often used to describe smells
Usage: The pungent odor in the classroom made Joseph lose his concentration during the test.
fetid
Meaning: having a foul odor
Usage: I can tell from the fetid smell in your refrigerator that your milk has spoiled.
rancid
Meaning: having a terrible taste or smell
Usage: Rob was double-dog-dared to eat the rancid egg salad sandwich.
noisome
Meaning: unpleasant, offensive, especially to the sense of smell
Usage: Nobody would enter the stalls until the horse’s noisome leavings were taken away.
putrid
Meaning: rotten, foul
Usage: Those rotten eggs smell putrid.