sourer; sourest
1
: having an acid taste that is like the taste of a lemon : tart
sour pickles
a sour apple
a slightly sour taste
2
: having the unpleasant taste or smell of food that is no longer fresh
The milk had turned/gone sour.
The cream smells sour.
a sour odor
sour [=bad] breath
3
: unpleasant or unfriendly
a sour, cynical person
He made a sour face.
Their relationship ended on a sour note. [=ended unpleasantly]
4
informal
: bad or wrong
Their relationship had turned/gone sour.
All their investments went sour.
sours; soured; souring
1
of food
: to lose freshness and get an unpleasant taste or smell : to become sour
The milk soured quickly.
2
a
: to become unpleasant or unfriendly
Her disposition has soured in recent years.
Their friendship has soured. [=they are no longer friends]
b
: to make (someone or something) unpleasant or unfriendly
Jealousy has soured their relationship.
His experiences have soured him.
3
: to make (something good) less pleasant or enjoyable
The team's victory was soured by an injury to one of their best players.
Cite this Entry
“Sour.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/sour. Accessed 17 Apr. 2026.
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