head-on vs indirect

head-on

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

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

noun
  • A collision from the front. 

adv
  • With the front of a vehicle. 

  • With direct confrontation. 

indirect

verb
  • To access by means of indirection; to dereference. 

noun
  • An indirect cost. 

  • An indirect radiator 

adj
  • Not of obvious or immediate cause, but as a secondary result 

  • Not focused straight at the target or subject, but by more subtle means 

  • Not involving the quickest, shortest, or most convenient path 

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