keel vs overfall

keel

verb
  • to collapse, to fall 

  • To turn up the keel; to show the bottom. 

  • To traverse with a keel; to navigate. 

  • To mark with ruddle. 

noun
  • A broad, flat vessel used for cooling liquids; a brewer's cooling vat; a keelfat. 

  • In a dirigible, a construction similar in form and use to a ship's keel; in an aeroplane, a fin or fixed surface employed to increase stability and to hold the machine to its course. 

  • A large beam along the underside of a ship’s hull from bow to stern. 

  • The two lowest petals of the corolla of a papilionaceous flower, united and enclosing the stamens and pistil; a carina. 

  • A rigid, flat piece of material anchored to the lowest part of the hull of a ship to give it greater control and stability. 

  • Red chalk; ruddle. 

  • The rigid bottom part of something else, especially an iceberg. 

  • A type of flat-bottomed boat. 

  • The periphery of a whorl extended to form a more or less flattened plate; a prominent spiral ridge. 

overfall

verb
  • To fall over; to topple. 

  • To fall on or spill over so as to cover (something). 

  • To change or affect so as to pervade (something); to come over 

  • To fall over; to spill from an edge or height. 

noun
  • Part of a garment that hangs so as to cover a lower part. 

  • A turbulent section of a body of water, caused by strong currents passing over submerged ridges. 

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