sour

1 of 4

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 4

noun (1)

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 4

verb

soured; souring; sours

intransitive verb

: to become sour

transitive verb

: to make sour

sourness

4 of 4

noun (2)

sour·​ness

plural -es

1

: the quality, state, or degree of being sour : acidity

2

: discontent, peevishness

Synonyms of sour

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

But with the concerns surrounding high-profile security breaches escalating, and public sentiment toward AI companies turning decidedly sour heading into the November midterm elections, calls for regulation are only likely to grow louder. — Ari Levy, CNBC, 30 Sep. 2026

And members of these new churches were mostly not the black-dressed, hypocritical, sour-faced, monocultural figures favored by popular narrative, but often included colorful figures who were sometimes surprisingly modern in their desires. — Literary Hub, 28 Sep. 2026

Noun

Today’s tycoons learn a lesson from history — public esteem for rich entrepreneurs inevitably sours, columnist Michael Hiltzik argues. — Kevinisha Walker, Los Angeles Times, 8 Sep. 2026

Tart, bright, and fresh, this is essentially a gin sour with a plush kiss of blackberry liqueur, made extra refreshing by crushed ice. — Jeremy Repanich, Robb Report, 15 Aug. 2026

Verb

Views of Canada in particular have soured amid a trade war between the two countries. — Miles J. Herszenhorn, USA Today, 22 Sep. 2026

The co-opting of Hispanic Heritage Month by companies like these have soured me on the celebration for years now. — Carlos De Loera, Los Angeles Times, 18 Sep. 2026

Word History

Etymology

Adjective

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

Noun (2)

Middle English sournes, from Old English sūrness, from sūr + -ness

First Known Use

Adjective

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

Noun (1)

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