head-on vs sincere

head-on

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

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

adv
  • With the front of a vehicle. 

  • With direct confrontation. 

noun
  • A collision from the front. 

sincere

adj
  • Meant truly or earnestly. 

  • Genuine; meaning what one says or does; heartfelt. 

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