diacritic vs quotation mark

diacritic

noun
  • A special mark added to a letter to indicate a different pronunciation, stress, tone, or meaning. 

adj
  • distinguishing 

  • Denoting a distinguishing mark applied to a letter or character. 

quotation mark

noun
  • One of a pair of quotation marks used to denote a quotation in writing. The same symbol is now typically used at both the beginning and the end of the quotation, which is usually the "double quotes" or "straight quotes" symbol ", although the "single quote" or "straight quote" symbol ' is sometimes used, especially to denote a quotation within a quotation. 

  • One of a pair of quotation marks used to denote a quotation in writing. The symbol used at the beginning of the quotation ("opening quotation mark") is usually “ ("open inverted commas") or ‘ ("open inverted comma"), and the symbol at the end ("closing quotation mark") is ” ("close inverted commas") or ’ ("close inverted comma"). 

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