flip-flop vs instep

flip-flop

noun
  • A sandal consisting of a rubber sole fastened to the foot by a rubber thong fitting between the toes and around the sides of the foot. 

  • A return trip. 

  • A bistable; an electronic switching circuit that has either two stable states (switching between them in response to a trigger) or a stable and an unstable state (switching from one to the other and back again in response to a trigger), and which is thereby capable of serving as one bit of memory. 

  • An instance of flip-flopping, of repeatedly changing one's stated opinion about a matter. 

  • A change of places; an inversion or swap. 

  • The sound of a regular footfall. 

  • A somersault. 

verb
  • To alternate back and forth between directly opposite opinions, ideas, or decisions. 

instep

noun
  • A section of any footwear covering that part of the foot. 

  • In horses, the hind leg from the ham to the pastern joint. 

  • The arched part of the top of the foot between the toes and the ankle. 

How often have the words flip-flop and instep occurred in a corpus of books? (source: Google Ngram Viewer )