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.
(of a person's character) Peevish or bad-tempered.
He gave me a sour look.
(of soil) Excessively acidic and thus infertile.
a sour marsh
(of petroleum) Containing excess sulfur.
sour gas smells like rotten eggs
Unfortunate or unfavorable.
Off-pitch, out of tune.
That which makes something sour.