The sensation of a sour taste.

A drink made with whiskey, lemon or lime juice and sugar.

(by extension) Any cocktail containing lemon or lime juice.

To make sour.

“Too much lemon juice will sour the recipe.”

To become sour.

To spoil or mar; to make disenchanted.

Having an acidic, sharp or tangy taste.

“Lemons have a sour taste.”

Made rancid by fermentation, etc.

“Don't drink that milk; it's turned sour.”

Tasting or smelling rancid.

“His sour breath makes it unpleasing to talk to him.”