belly vs threshold

belly

noun
  • The lower fuselage of an airplane. 

  • The stomach. 

  • The main curved portion of a knife blade. 

  • The abdomen, especially a fat one. 

  • The part of anything which resembles (either closely or abstractly) the human belly in protuberance or in concavity; often, the fundus (innermost part). 

  • The womb. 

  • The hollow part of a curved or bent timber, the convex part of which is the back. 

verb
  • To swell and become protuberant; to bulge or billow. 

  • To cause to swell out; to fill. 

  • To position one’s belly; to move on one’s belly. 

threshold

noun
  • The start of the landing area of a runway. 

  • The outset of something; the point of entry, or the beginning of an action. 

  • The bottom-most part of a doorway that one crosses to enter; a sill. 

  • The point where one mentally or physically is vulnerable in response to provocation or to particular things in general. As in emotions, stress, or pain. 

  • An entrance; the door or gate of a house. 

  • The quantitative point at which an action is triggered, especially a lower limit. 

  • Any end or boundary. 

  • The wage or salary at which income tax becomes due. 

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