head-on vs immovable

head-on

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

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

noun
  • A collision from the front. 

adv
  • With the front of a vehicle. 

  • With direct confrontation. 

immovable

adj
  • steadfast in purpose or intention; unalterable, unyielding 

  • not capable of being affected or moved in feeling; impassive 

  • not liable to be removed; permanent in place or tenure; fixed 

  • incapable of being physically moved; fixed 

noun
  • that which can not be moved; something which is immovable 

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