expansion vs stretching

expansion

noun
  • An act, process, or instance of expanding. 

  • A new addition. 

  • A product to be used with a previous product. 

  • That which is expanded; expanse; extended surface. 

  • The operation of steam in a cylinder after its communication with the boiler has been cut off, by which it continues to exert pressure upon the moving piston. 

  • The replacement of a short name (e.g., acronym, initialism, alphanumeric symbol, abbreviation) with the longer name that is synonymous with it, as when spelling out acronyms to ensure clarity for a general audience. 

  • The string of text thus substituted. 

  • The fractional change in unit length per unit length per unit temperature change. 

stretching

noun
  • The act by which something is stretched. 

  • A form of physical exercise in which a specific skeletal muscle (or muscle group) is deliberately elongated to its fullest length in order to improve the muscle's felt elasticity and reaffirm comfortable muscle tone. 

adj
  • Requiring a high level of effort or performance. 

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