firsthand vs head-on

firsthand

adj
  • Direct, without intermediate stages. 

  • Not previously owned or used; contrasted with secondhand. 

adv
  • Directly or from personal experience. 

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. 

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