contiguous vs head-on

contiguous

adj
  • Connected; touching; abutting. 

  • Adjacent; neighboring. 

  • Connecting without a break. 

head-on

adj
  • Of a collision, from the front or in the direction of motion. 

  • Direct, abrupt, blunt or unequivocal; not prevaricating. 

adv
  • With the front of a vehicle. 

  • With direct confrontation. 

noun
  • A collision from the front. 

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