involute vs twirl

involute

verb
  • To roll or curl inwards. 

adj
  • Turned inward at the margin, like the exterior lip of the shells of species in genus Cypraea. 

  • Difficult to understand; complicated. 

  • Having a complex pattern of coils in which younger whorls only partly surround older ones. 

  • Rolled inward spirally. 

  • Having the edges rolled with the adaxial side outward. 

noun
  • A curve that cuts all tangents of another curve at right angles; traced by a point on a string that unwinds from a curved object. 

twirl

verb
  • To twist round. 

  • To pitch. 

  • To rotate rapidly. 

  • To perform a twirl. 

noun
  • A little twist of some substance; a swirl. 

  • A movement where a person spins round elegantly; a pirouette. 

  • Any rotating movement; a spin. 

  • A prison guard. 

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