bole vs tree fork

bole

noun
  • The trunk or stem of a tree. 

  • Any of several varieties of friable earthy clay, usually coloured red by iron oxide, and composed essentially of hydrous silicates of alumina, or more rarely of magnesia. 

  • An aperture with a shutter in the wall of a house, to admit air or light. 

  • A small closet. 

  • The shade of reddish brown which resembles this clay. 

tree fork

noun
  • A bifurcation in the trunk of a tree giving rise to two roughly equal diameter branches. 

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