A sensation, pleasant or unpleasant, detected by inhaling air (or, the case of water-breathing animals, water) carrying airborne molecules of a substance.

“I love the smell of fresh bread.”

The sense that detects odours.

A conclusion or intuition that a situation is wrong, more complex than it seems, or otherwise inappropriate.

To sense a smell or smells.

“I can smell fresh bread.”

Followed by like or of if descriptive: to have a particular smell, whether good or bad.

“Her feet smell of cheese.”

(without a modifier) To smell bad; to stink.

“Ew, this stuff smells.”