head-on vs head-on collision

head-on

noun
  • A collision from the front. 

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. 

head-on collision

noun
  • A collision where the front ends of two vehicles (such as ships, trains, cars, planes, etc.) hit each other, as opposed to a side-collision or rear-end collision. 

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