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
3
a
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
1
a
: something sour
… they assimilated many Anglo-American sweet pickles and began adding more sugar to their sours.—
William Woys Weaver
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
soured; souring; sours
: to become sour
: to make sour
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
Ryan Coleman, Entertainment Weekly, 5 Jan. 2026
But, more importantly, its heavy, sour crude is extraordinarily cheap, nearby to the United States and able to be refined into key derivatives for US industry, including asphalt, heating oil and diesel.
—David Goldman, CNN Money, 5 Jan. 2026
Sacbee.com, 29 Dec. 2025
Until a settlement, the litigation provides a window into the relationship between majority and minority owners and what happens when that relationship sours.
—Michael McCann, Sportico.com, 29 Dec. 2025
Aimee Picchi, CBS News, 31 Dec. 2025
Things soured between the two of them in October 1982, the final time Allen guest hosted.
—Lori A Bashian, FOXNews.com, 22 Dec. 2025
See All Example Sentences for sour
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Adjective
Though Monica is on course to play a bigger role than ever in season 8, a sour meal in the Czech capital city nearly took her off track.
—Ryan Coleman, Entertainment Weekly, 5 Jan. 2026
But, more importantly, its heavy, sour crude is extraordinarily cheap, nearby to the United States and able to be refined into key derivatives for US industry, including asphalt, heating oil and diesel.
—David Goldman, CNN Money, 5 Jan. 2026
Noun
Mraz Brewing was well-known for its award-winning Belgian-style ales and fruit sours.
—Sacbee.com, 29 Dec. 2025
Until a settlement, the litigation provides a window into the relationship between majority and minority owners and what happens when that relationship sours.
—Michael McCann, Sportico.com, 29 Dec. 2025
Verb
Such bubbles — when stock valuations run far ahead of underlying fundamentals — can set the stage for sharp market corrections if investor sentiment sours.
—Aimee Picchi, CBS News, 31 Dec. 2025
Things soured between the two of them in October 1982, the final time Allen guest hosted.
—Lori A Bashian, FOXNews.com, 22 Dec. 2025
See All Example Sentences for sour
Cite this Entry
“Sour.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sour. Accessed 6 Jan. 2026.
Copy CitationKids Definition
sour
1 of 3 adjective1
: 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 noun1
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
: 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
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