(n.) The quality or state of being sour.

Faustianism acerbity acidity acidulousness acridity acridness acrimony anger animosity animus asperity astringence astringency atonalism atonality bad blood bad humor bad temper bile biliousness bitingness bitter feeling bitter pill bitterness cacophony causticity choler clinker cold comfort corrosiveness cuttingness disappointment discontent discontentedness discontentment discord discordance discordancy disgruntlement disharmony dissatisfaction dissatisfiedness dissonance dissonancy dissonant chord divine discontent edge envy feud flatness gall gall and wormwood hard feelings harshness ill blood ill feeling ill humor ill nature ill temper ill will inharmoniousness inharmony keenness mordancy off note peevishness petulance piquancy poignancy pungency querulousness rancor rebelliousness resentment restiveness restlessness roughness severity sharpness soreness sour note spleen stridor sulkiness tartness trenchancy tunelessness uneasiness unfulfillment unhappiness unharmoniousness unmusicality unpleasure unsatisfaction untunefulness vendetta venom vexation of spirit virulence vitriol wolf