sour
US /saʊr/
UK /saʊr/

1.
2.
unpleasant or unfriendly
:
•
The meeting ended on a sour note.
•
Their relationship turned sour after the argument.
1.
become unpleasant, acrimonious, or unfriendly
:
•
Their friendship began to sour after the misunderstanding.
•
The milk will sour if left out of the fridge.