elongation vs extension lead

elongation

noun
  • The ratio of the extension of a material to the length of the material prior to stretching. 

  • The act of lengthening 

  • the state of being lengthened 

  • Removal to a distance; withdrawal; a being at a distance; distance. 

  • The angular distance of a planet from the sun 

  • That which lengthens out; continuation. 

extension lead

noun
  • extension cord 

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