ferrous vs insensible

ferrous

adj
  • Of or containing iron. 

  • Of compounds of iron in which it has a valence or oxidation number of 2. 

insensible

adj
  • Incapable or deprived of physical sensation. 

  • Unable to be perceived by the senses. 

  • Incapable of mental feeling; indifferent. 

  • Not sensible or reasonable; meaningless. 

  • Incapable of emotional feeling; callous; apathetic. 

  • Unable to be understood; unintelligible. 

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