1. Having a taste characteristic of that produced by acids; sharp, tart, or tangy.
2. Made acid or rancid by fermentation.
3. Having the characteristics of fermentation or rancidity; tasting or smelling of decay.
a. Bad-tempered and morose; peevish: a sour temper.
b. Displeased with something one formerly admired or liked; disenchanted: sour on ballet.
a. Not measuring up to the expected or usual ability or quality; bad.
b. Not having the correct or properly produced pitch: a sour note.
6. Of or relating to excessively acid soil that is damaging to crops.
7. Containing excessive sulfur compounds. Used of gasoline.
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.
tr. & intr.v. soured, sour·ing, sours
1. To make or become sour.
2. To make or become disagreeable, disillusioned, or disenchanted.
1. having or denoting a sharp biting taste like that of lemon juice or vinegar Compare bitter 
2. (Miscellaneous Technologies / Brewing) made acid or bad, as in the case of milk or alcohol, by the action of microorganisms
3. having a rancid or unwholesome smell
4. (of a person's temperament) sullen, morose, or disagreeable
5. (Earth Sciences / Physical Geography) (esp of the weather or climate) harsh and unpleasant
6. disagreeable; distasteful a sour experience
7. (Life Sciences & Allied Applications / Agriculture) (of land, etc.) lacking in fertility, esp due to excessive acidity
8. (Chemistry) (of oil, gas, or petrol) containing a relatively large amount of sulphur compounds
go or turn sour to become unfavourable or inharmonious his marriage went sour
1. something sour
2. (Miscellaneous Technologies / Brewing) Chiefly US any of several iced drinks usually made with spirits, lemon juice, and ice a whiskey sour
3. (Clothing, Personal Arts & Crafts / Tanning) an acid used in laundering and bleaching clothes or in curing animal skins