nonchalance vs tenseness

nonchalance

noun
  • Indifference, unconcern; carelessness; coolness; disregard, detachment. 

tenseness

noun
  • A particular vowel or consonant quality that is phonemically contrastive in many languages, including English. 

  • The characteristic of being tense. 

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