flexure vs hairpin curve

flexure

noun
  • The act of bending or flexing; flexion. 

  • A turn; a bend; a fold; a curve. 

  • A curve or bend in a tubular organ. 

  • The last joint, or bend, of the wing of a bird. 

  • The small distortion of an astronomical instrument caused by the weight of its parts; the amount to be added or subtracted from the observed readings of the instrument to correct them for this distortion. 

verb
  • To introduce a flexure into; to bend or flex. 

hairpin curve

noun
  • Synonym of hairpin bend 

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