head-on vs thoughtless

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. 

thoughtless

adj
  • Inconsiderate, inattentive. 

  • Lacking thought or consideration. 

  • Marked by or showing lack of due thought or care; careless. 

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