flat twist vs torsion

flat twist

noun
  • Synonym of hair twist 

torsion

noun
  • The act of turning or twisting, or the state of being twisted; the twisting or wrenching of a body by the exertion of a lateral force tending to turn one end or part of it about a longitudinal axis, while the other is held fast or turned in the opposite direction. 

  • That force with which a thread, wire, or rod of any material returns, or tends to return, to a state of rest after it has been twisted; torsibility. 

  • The stopping of arterial haemorrhage in certain cases, by twisting the cut end of the artery. 

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