sourness
US /ˈsaʊr.nəs/
UK /ˈsaʊr.nəs/

1.
the quality of being sour; acidity.
:
•
The sourness of the lemon made her eyes water.
•
He added sugar to reduce the sourness of the sauce.
2.
a disagreeable or unpleasant quality or disposition.
:
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There was a certain sourness in his tone when he spoke about his ex-colleague.
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The constant criticism led to a general sourness in their relationship.