sour

inaccurate in pitch

“a false (or sour) note”

having a sharp biting taste

one of the four basic taste sensations; like the taste of vinegar or lemons

smelling of fermentation or staleness

the property of being acidic

showing a brooding ill humor

“a sour temper”

in an unpalatable state

“sour milk”

go sour or spoil

“The milk has soured”

the taste experience when vinegar or lemon juice is taken into the mouth

make sour or more sour

a cocktail made of a liquor (especially whiskey or gin) mixed with lemon or lime juice and sugar