airway vs ductus

airway

noun
  • The trachea. 

  • A flight path used by aeroplanes. 

ductus

noun
  • a duct, tube or canal in the body 

  • a subtle reduction of weight towards the middle of the stroke of the letter 

  • the number of strokes that make up a written letter, and the direction, sequence and speed in which they are written (Compare graph; see also aspect.) 

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