nodule vs tubercle

nodule

noun
  • A rounded mass or irregular shape; a little knot or lump. 

tubercle

noun
  • A round nodule, small eminence, or warty outgrowth, especially those found on bones for the attachment of a muscle or ligament or small elevations on the surface of a tooth. 

  • A small rounded nodule forming the characteristic lesion of tuberculosis. 

  • A small rounded wartlike protuberance of the roots of some leguminous plants; the lip of certain orchids, cacti. 

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