1. The sensation of sour taste, one of the four primary tastes. 2. Something sour. 3. A mixed drink made especially with whiskey, lemon or lime juice, sugar, and sometimes soda water., SOUR meaning: 1 : having an acid taste that is like the taste of a lemon tart; 2 : having the unpleasant taste or smell of food that is no longer fresh, Sour definition: Having a taste characteristic of that produced by acids; sharp, tart, or tangy., 1. Something that is sour has a sharp, unpleasant taste like the taste of a lemon. [] 2. See also sweet and sour 3. Sour milk is milk that has an unpleasant taste because it is no longer fresh. [], sour /saʊr, ˈsaʊɚ/ adj., -er, -est, n. adj. having an acid taste resembling that of vinegar; tart: Lemons taste sour. made into an acid or acidlike substance by fermentation; fermented: sour milk. resembling or suggesting something fermented: Some of the baby's clothes have a sour smell. distasteful or disagreeable; unpleasant: a few sour , Sour refers to something that has a taste resembling that of a lemon or vinegar, sharp and acidic. It can also describe a situation or behavior that is unpleasant or disagreeable..