head-on vs insistent

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. 

insistent

adj
  • Extorting attention or notice; coercively staring or prominent; vivid; intense. 

  • Urgent in dwelling upon anything; persistent in urging or maintaining. 

  • Standing on end: specifically said of the hind toe of a bird when its base is inserted so high on the shank that only its tip touches the ground: correlated with incumbent. 

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