1.Definition: having a sharp biting taste

2.Definition: in an unpalatable state

"Sour milk"

Related Adjective(s):off, turned

3.Definition: inaccurate in pitch

"A false (or sour) note"

Related Adjective(s):false

4.Definition: one of the four basic taste sensations; like the taste of vinegar or lemons

5.Definition: showing a brooding ill humor

"A sour temper"

Related Adjective(s):dark, dour, glowering, glum, moody, morose, saturnine, sullen

6.Definition: smelling of fermentation or staleness

Related Adjective(s):rancid