ambulant vs on foot

ambulant

adj
  • Able to walk. 

  • Designed for use by somebody with a disability that impairs, but does not prevent, walking. 

noun
  • A patient who is able to walk. 

on foot

prep
  • In progress or in preparation; active, in operation. 

  • On one's feet; walking, jogging or running but not in a vehicle or on the back of an animal. 

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