Aroma is the word for a fragrant scent, one that pleases the nose in a way that makes you lick your lips. Unlike its foul-smelling cousin the odor, an aroma smells but never stinks.
Want to know what aromas smell like? Brew a fresh pot of coffee, grill some onions, and fry up a few strips of bacon. Aromas make you drool. You can also use the word to describe things that don't literally smell, yet somehow seem to linger smell-like in the air, like the oppressive aroma of a brutal dictatorship.