aftarm vs cubit

aftarm

noun
  • The part of the arm between the shoulder and the elbow. 

cubit

noun
  • The distance from the elbow to the tip of the middle finger used as an informal unit of length. 

  • Any of various units of length approximating this distance, usually around 35–60 cm. 

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