acerbity vs acidness

acerbity

noun
  • Sourness of taste, with bitterness and astringency, like that of unripe fruit. 

  • Harshness, bitterness, or severity 

  • Something harsh (e.g. a remark, act or experience). 

acidness

noun
  • acidity, sourness 

How often have the words acerbity and acidness occurred in a corpus of books? (source: Google Ngram Viewer )