Adjective
1. smelling of fermentation or staleness
2. having a sharp biting taste
3. one of the four basic taste sensations; like the taste of vinegar or lemons
4. in an unpalatable state;
"sour milk"5. inaccurate in pitch;
"a false (or sour) note""her singing was off key"6. showing a brooding ill humor;
"a dark scowl""the proverbially dour New England Puritan""a glum, hopeless shrug""he sat in moody silence""a morose and unsociable manner""a saturnine, almost misanthropic young genius"- Bruce Bliven"a sour temper""a sullen crowd"