discoid vs kneecap

discoid

noun
  • A disk-shaped dental excavator designed to remove the carious dentin of a decayed tooth 

adj
  • Shaped like a disc/disk. 

kneecap

noun
  • A metal cover trim that fits over a panel rib after it has been cut and bent. 

  • The flat, roundish bone in the knee. 

  • A cap or strong covering for the knees, used chiefly for horses, to protect their knees in case of a fall. 

verb
  • To destroy the knees of (a person), usually by shooting at the knees, as a punishment carried out by criminals or terrorists. 

  • To attack (someone) in a way that is excessively and needlessly damaging: To cut (someone) off at the knees. 

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