sour

[1]	turn , ferment , work
[2]	acidify , turn , spoil , acidulate , acetify , curdle , go bad/off , ferment
[3]	embitter , acerbate , disenchant , exasperate , vex , (Colloq) peeve

[1]	sourness , tartness
[2]	sourness , acidity

adj.

[1]	acid , acidic , tart , vinegary , lemony , acidulous/acidulent , acidulated , acescent , acerbic
[2]	turned , bad , (gone) off , fermented , curdled , rancid , spoilt/spoiled
[3]	disagreeable , unpleasant , distasteful , bad , nasty , bitter , terrible
[4]	acrimonious , bitter , embittered , unpleasant , churlish , ill-natured , ill-tempered , bad-tempered , crusty , curmudgeonly , crabbed , crabby , grouchy , cross , cranky , testy , petulant , impatient , abrupt , nasty , curt , caustic , brusque , peevish , snappish , edgy , sullen , morose , gloomy , discontented
[5]	rancid
[6]	off , turned
[7]	false , off-key
[8]	dark , dour , glowering , glum , moody , morose , saturnine , sullen