insistent vs unswervable

insistent

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

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

  • 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. 

unswervable

adj
  • Not swervable. 

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