sour

1 of 3

adjective

ˈsau̇(-ə)r 

1

: being, inducing, or marked by the one of the five basic taste sensations that is produced chiefly by acids and is characteristic of lemon juice

sour pickles

compare bitter entry 1 sense 1a, salty entry 1 sense 1b, sweet entry 1 sense 1, umami entry 2

2

a(1)

: having the acid taste or smell of or as if of fermentation : turned

sour milk

(2)

: of or relating to fermentation

b

: smelling or tasting of decay : rancid, rotten

sour breath

c(1)

: bad, wrong

a project gone sour

(2)

: hostile, disenchanted

went sour on Marxism

3

a

: unpleasant, distasteful

b

: cross, sullen

c

: not up to the usual, expected, or standard quality or pitch

4

: acid in reaction

—used especially of soil

5

: containing malodorous sulfur compounds

—used especially of petroleum products

sourish

ˈsau̇(-ə)r-ish 

adjective

sourly adverb

sourness noun

sour

2 of 3

noun

1

a

: something sour

… they assimilated many Anglo-American sweet pickles and began adding more sugar to their sours.

—William Woys Weaver

b

: the taste sensation produced chiefly by acids compare bitter entry 2 sense 1b, salty entry 2, sweet entry 3 sense 2, umami entry 1

2

: a cocktail consisting of a liquor (such as whiskey), lemon or lime juice, sugar, and sometimes ice

sour

3 of 3

verb

soured; souring; sours

intransitive verb

: to become sour

transitive verb

: to make sour

Synonyms

Adjective

• acidic
• acid

Verb

• anger
• alien
• infuriate
• outrage
• alienate

Examples of sour in a Sentence

Adjective

The milk had turned sour.

He made a sour face.

Verb

Her disposition has soured in recent years.

Jealousy has soured their relationship.

His experiences have soured him.

The team's victory was soured by an injury to one of their best players.

Recent Examples on the Web

Adjective

Younger customers have been gravitating toward chewy, sweet treats – sales of sour candy, for example, grew 7% year over year, according to the National Confectioners Association. —Ramishah Maruf, CNN Money, 26 Oct. 2025

Even if every play causes a sour visage on his face, Bichette is helping the Blue Jays on their quest for a title. —Fabian Ardaya, New York Times, 25 Oct. 2025

Noun

The Midnight riff comes to us from Sam Ross, then of the legendary Milk & Honey, and turns the classic into a sour, bringing lemon juice to tart up the old Stinger profile but subbing bourbon for Cognac and Fernet Branca for the mint liqueur. —Jeremy Repanich, Robb Report, 25 Oct. 2025

If investor sentiment around AI sours, or if progress stalls owing to technological bottlenecks or supply constraints, equity prices could tumble—and, given the degree of market concentration, such an adjustment would ripple rapidly through broad market indices, affecting millions of investors. —Jessica Coacci, Fortune, 8 Oct. 2025

Verb

Sentiment among investors and consumers could sour as uncertainty looms over the economy, some economists warned, noting a feedback loop as participants brace for further pain and the ensuing pullback triggers sluggish economic performance. —Max Zahn, ABC News, 24 Oct. 2025

Views of Trump have even soured a little among Hispanic Republicans. —Preston Fore, Fortune, 24 Oct. 2025

Word History

Etymology

Adjective

Middle English, from Old English sūr; akin to Old High German sūr sour, Lithuanian sūrus salty

First Known Use

Adjective

before the 12th century, in the meaning defined at sense 1

Noun

before the 12th century, in the meaning defined at sense 1a

Verb

14th century, in the meaning defined at intransitive sense

Phrases Containing sour

• on a sour note
• sour ball
• sour cherry
• sour cream
• sour grapes
• sour grass
• sour gum
• sour mash
• sour on
• sour orange
• sweet-and-sour
• whiskey sour

Rhymes for sour

• airpower
• brainpower
• devour
• empower
• firepower
• horsepower
• manpower
• mayflower
• safflower
• sunflower
• wallflower
• watchtower

Kids Definition

sour

1 of 3 adjective

ˈsau̇(ə)r 

1

: having or being an acid or tart taste that is one of the four taste sensations compare bitter sense 1, salt entry 3 sense 1b, sweet entry 1 sense 1b

2

a

: having become acid through spoiling

sour milk

b

: indicating decay : putrid

a sour odor

3

: unpleasant, disagreeable

a sour look

played a sour note

4

: acid in reaction

sour soil

sourly adverb

sourness noun

sour

2 of 3 noun

1

a

: something sour

b

: the basic taste sensation produced by acid stimuli

2

: a cocktail made with liquor, lemon or lime juice, sugar, and sometimes soda water

sour

3 of 3 verb

: to become or make sour

Medical Definition

sour

1 of 2 adjective

ˈsau̇(ə)r 

: causing, characterized by, or being the one of the four basic taste sensations that is produced chiefly by acids compare bitter, salt entry 2 sense 2, sweet entry 1

sourness noun

sour

2 of 2 noun

: the primary taste sensation produced by acid stimuli