big toe vs unguis

big toe

noun
  • The largest toe (usually) on each human foot (i.e. the toe closest to the other foot when the feet are flat on the ground, side by side, and the legs not crossed) or on a foot of certain other animals. 

unguis

noun
  • The nail, claw, talon, or hoof of a finger, toe, or other appendage. 

  • The slender base of a petal in some flowers; a claw; an ungula. 

  • An old measure equal to the length of the nail of the little finger. 

  • One of the terminal hooks on the foot of an insect. 

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