Centaur vs rider

Centaur

noun
  • A skillful horseman or horsewoman. 

  • One of a race of monsters having a head, torso, and arms of a man, and the body and legs of a horse. Often depicted as rowdy drunkards, with Chiron being a notable exception. 

  • A U.S. upper stage, with a restartable liquid-propellant engine, used with an Atlas or Titan booster to launch satellites and probes. 

  • An icy planetoid that orbits the Sun between Jupiter and Neptune 

rider

noun
  • Someone who rides a horse or (later) a bicycle, motorcycle etc. 

  • An amendment or addition to an entertainer's performance contract, often covering a performer's equipment or food, drinks, and general comfort requirements. 

  • A small, sliding piece of thin metal on a balance, used to determine small weights. 

  • Someone riding in a vehicle; a passenger on public transport. 

  • A supplementary question, now especially in mathematics. 

  • An interior rib occasionally fixed in a ship's hold, reaching from the keelson to the beams of the lower deck, to strengthen the frame. 

  • The first Lenormand card, also known as either the horseman or the cavalier. 

  • The second tier of casks in a vessel's hold. 

  • A supplementary clause added to a document after drafting, especially to a bill under the consideration of a legislature. 

  • An old Dutch gold coin with the figure of a man on horseback stamped upon it. 

  • A knight, or other mounted warrior. 

  • An additional matter or question arising in corollary; a qualification. 

  • A piece, such as the rook or bishop, which moves any distance in one direction, as long as no other piece is in the way. 

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