acidity

noun4

1. •
   The quality or state of being acid.
2. •
   Sourness; tartness; sharpness to the taste.

   • Empty stomachs lead to acidity and leave a sour taste in the mouth.
3. •
   Excessive acid quality, as in gastric secretions.
4. •
   (figurative) A caustic, sour, biting, or bitter quality.

   • "What shall we call it?" he asked. "Why should you not take the chance of perpetuating your own name?" said Summerlee, with his usual touch of acidity. — 1912