- having the sharp, acid taste of lemon juice, vinegar, green fruit, etc.
- made acid or rank by or as by fermentation: sour milk
- cross, bad-tempered, peevish, morose, etc.: a sour mood
- ill-disposed and bitter: sour toward former associates
- below what is usual or normal; poor; bad: his game has gone sour
- distasteful or unpleasant
- gratingly wrong or off pitch: a sour note
- excessively acid: said of soil
- tainted with sulfur compounds: said of gasoline, etc.
ME soure < OE sur, akin to Ger sauer, ON sūrr < IE *suro-, sour, salty > Latvian sũrs, salty, bitter
transitive verb, intransitive verb
to make or become sour: the milk will sour, soured on life