sour

American  

[sou^uhr, sou-er] / saʊər, ˈsaʊ ər /

adjective

sourer, sourest

1. having an acid taste, resembling that of vinegar, lemon juice, etc.; tart.

   Antonyms:

   sweet

2. rendered acid or affected by fermentation; fermented.

3. producing the one of the four basic taste sensations that is not bitter, salt, or sweet.

4. characteristic of something fermented.

   a sour smell.

5. distasteful or disagreeable; unpleasant.

   Synonyms:

   unsatisfactory, subpar, suboptimal, bitter

6. below standard; poor.

   It was a sour effort all around, the kind of effort that doesn't exactly inspire confidence.

7. harsh in spirit or temper; acrimonious; disagreeable; peevish.

   Synonyms:

   severe, crabbed, petulant, cross, touchy, testy

8. Agriculture. (of soil) having excessive acidity.

9. (of gasoline or the like) contaminated by sulfur compounds.

10. Music. off-pitch; badly produced.

    a sour note.

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noun

1. something that is sour.

2. any of various cocktails consisting typically of whiskey or gin with lemon or lime juice and sugar and sometimes soda water, often garnished with a slice of orange, a maraschino cherry, or both.

3. any of various beers with a particularly acidic or tart taste, made so by acid-producing bacteria and yeast in the brew.

   Sours are a good choice to go with deep-fried bar food.

4. an acid or an acidic substance used in laundering and bleaching to neutralize alkalis and to decompose residual soap or bleach.

verb (used without object)

1. to become sour, rancid, mildewed, etc.; spoil.

   Milk sours quickly in warm weather. The laundry soured before it was ironed.

2. to become unpleasant or strained; worsen; deteriorate.

   Relations between the two countries have soured.

3. to become bitter, disillusioned, or disinterested.

   I guess I soured when I learned he was married.

   My loyalty soured after his last book.

4. Agriculture. (of soil) to develop excessive acidity.

verb (used with object)

1. to make sour; cause sourness in.

   What do they use to sour the mash?

2. to cause spoilage in; rot.

   Defective cartons soured the apples.

3. to make bitter, disillusioned, or disagreeable.

   One misadventure needn't have soured him. That swindle soured a great many potential investors.

sour ¹ British  

/ ˈsaʊə /

adjective

1. having or denoting a sharp biting taste like that of lemon juice or vinegar Compare bitter

2. made acid or bad, as in the case of milk or alcohol, by the action of microorganisms

3. having a rancid or unwholesome smell

4. (of a person's temperament) sullen, morose, or disagreeable

5. (esp of the weather or climate) harsh and unpleasant

6. disagreeable; distasteful

   a sour experience

7. (of land, etc) lacking in fertility, esp due to excessive acidity

8. (of oil, gas, or petrol) containing a relatively large amount of sulphur compounds

9. to become unfavourable or inharmonious

   his marriage went sour

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noun

1. something sour

2. any of several iced drinks usually made with spirits, lemon juice, and ice

   a whiskey sour

3. an acid used in laundering and bleaching clothes or in curing animal skins

verb

1. to make or become sour

Sour ² British  

/ sʊə /

noun

1. a variant spelling of Sur

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Other Word Forms

• oversour adjective
• oversourly adverb
• oversourness noun
• sourish adjective
• sourly adverb
• sourness noun
• unsour adjective
• unsourly adverb
• unsourness noun

Etymology

Origin of sour

First recorded before 1000; Middle English adjective and noun sure, soure, Old English adjective sūr; cognate with German sauer, Dutch zuur, Old Norse sūrr

Explanation

If something is sour, it has a tangy or sharp flavor, like a lemon. Your brother may love the taste of limes, while they're way too sour for you. Sometimes this adjective is used to describe a fermented odor (the way milk smells when it goes bad), or a wrong note in music, or even a terrible mood: "Mom was acting so sour that I didn't even ask her if we could have pizza for dinner." Sour comes from the Old English sur, "sour, tart, or fermented."

Example Sentences

The end of the war would be good news for the broader market—but one of 2026’s hottest trades may be about to go sour.

From Barron's • Apr. 1, 2026

Many good coffee cake recipes lean on sour cream, which lends a pleasing density and richness to the batter.

From Salon • Mar. 31, 2026

However, relations between the founder of petrochemicals giant Ineos and Ainslie reportedly turned sour and they split at the start of last year.

From BBC • Mar. 21, 2026

Regulation requires banks to set aside money in case loans go sour or markets tank.

From The Wall Street Journal • Mar. 20, 2026

I asked, fighting the urge to laugh at the sour, pinched look on his face.

From "Glitch" by Laura Martin

Related Words

• acid
• acidic
• acrid
• biting
• bitter
• briny
• caustic
• fermented
• musty
• peppery
• piquant
• pungent
• rancid
• sharp
• soured
• unpleasant