flexible vs hairline

flexible

noun
  • Something that is flexible. 

adj
  • Capable or being adapted or molded in some way. 

  • Capable of being flexed or bent without breaking; able to be turned or twisted without breaking. 

  • Willing or prone to give way to the influence of others; not invincibly rigid or obstinate. 

hairline

noun
  • A very thin line in writing, drawing, or typography. 

  • A fishing line made from hair. 

  • The line along one's forehead where hair starts growing. 

  • A very thin fissure. 

adj
  • very thin, as thin as a hair 

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