back out vs curb

back out

verb
  • To undo (a change). 

  • To withdraw from something one has agreed to do. 

  • To exit a mode or function. 

  • To draw from behind the back [+accusative = a knife etc.] (as also bare back). 

  • Coordinate terms: cancel, call off, get cold feet 

  • To reverse (a vehicle) from a confined space. 

  • See also: sell short 

  • To dare (someone) to not withdraw from a challenge. 

  • To bet on someone losing. 

  • Coordinate term: scare off 

curb

verb
  • To rein in. 

  • To bend or curve. 

  • To furnish with a curb, as a well; to restrain by a curb, as a bank of earth. 

  • To crouch; to cringe. 

  • To damage vehicle wheels or tires by running into or over a pavement curb. 

  • To check, restrain or control. 

  • To bring to a stop beside a curb. 

noun
  • Something that checks or restrains; a restraint. 

  • A swelling on the back part of the hind leg of a horse, just behind the lowest part of the hock joint, generally causing lameness. 

  • A concrete margin along the edge of a road; a kerb (UK, Australia, New Zealand) 

  • A riding or driving bit for a horse that has rein action which amplifies the pressure in the mouth by leverage advantage placing pressure on the poll via the crown piece of the bridle and chin groove via a curb chain. 

  • A sidewalk, covered or partially enclosed, bordering the airport terminal road system with adjacent paved areas to permit vehicles to off-load or load passengers. 

  • A raised margin along the edge of something, such as a well or the eye of a dome, as a strengthening. 

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