lethargy vs tenseness

lethargy

noun
  • A state of extreme torpor or apathy, especially with lack of emotion, energy or enthusiasm; (loosely) sluggishness, laziness. 

  • A condition characterized by extreme fatigue or drowsiness, deep unresponsiveness, or prolonged sleep patterns. 

tenseness

noun
  • The characteristic of being tense. 

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

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