sour

adj

1. Tasting of acidity.

   “Lemons have a sour taste.”

   “All sour things, as vinegar, provoke appetite.”

   “A few types of molecules get sensed by receptors on the tongue. Protons coming off of acids ping receptors for "sour." Sugars get received as "sweet." Bitter, salty, and the proteinaceous flavor umami all set off their own neural cascades.”

2. Made rancid by fermentation, etc.

   “Don't drink that milk; it's turned sour.”

3. Tasting or smelling rancid.

   “His sour breath makes it unpleasing to talk to him.”

4. Hostile or unfriendly.

   “He gave me a sour look.”

   “He was a scholar […] / Lofty and sour to them that loved him not, / But to those men that sought him sweet as summer.”

5. Excessively acidic and thus infertile. (of soil)

   “sour land”

   “a sour marsh”

6. Containing excess sulfur. (of petroleum)

   “sour gas smells like rotten eggs”

7. Unfortunate or unfavorable.

   “Let me embrace thee, sour adversity”

   “The result may not quite give the Wearsiders a sweet ending to what has been a sour week, following allegations of sexual assault and drug possession against defender Titus Bramble, but it does at least demonstrate that their spirit remains strong in the face of adversity.”

8. Off-pitch, out of tune.

   “Unlike what the name implies, there is nothing inherently wrong with a sour note: It is perfectly well-tuned note that would sound normal in another context (and which presumably would not sound sour to someone unfamiliar with tonal music).”

noun

1. (countable, uncountable)The sensation of a sour taste.
2. (countable, uncountable)A drink made with whiskey, lemon or lime juice and sugar.
3. (broadly, countable, uncountable)Any cocktail containing lemon or lime juice.
4. (countable, uncountable)A sweet/candy having a sharply sour taste.

   ““You know I like them candies, especially the lemon sours.””

5. (countable, uncountable)A sour or acid substance; whatever produces a painful effect.

   “For many Years of Sorrow can dispense; A Dram of Sweet is worth a Pound of Sour”

6. (countable, uncountable)The acidic solution used in souring fabric.

verb

1. (transitive)To make sour.

   “Too much lemon juice will sour the recipe.”

2. (intransitive)To become sour.

   “So the sun's heat, with different powers, / Ripens the grape, the liquor sours.”

3. (transitive)To spoil or mar; to make disenchanted.

   “To sour your happiness I must report, / The queen is dead.”

   “He was prudent and industrious, and so good a husbandman, that he might have led a very easy and comfortable life, had not an arrant vixen of a wife soured his domestic quiet.”

4. (intransitive)To become disenchanted.

   “We broke up after our relationship soured.”

5. (transitive)To make (soil) cold and unproductive.

   “stagnant water , which tends to sour the soil”

6. To macerate (lime) and render it fit for plaster or mortar.
7. (transitive)To process (fabric) after bleaching, using hydrochloric acid or sulphuric acid to wash out the lime.