generator vs piston

generator

noun
  • An apparatus in which vapour or gas is formed from a liquid or solid by means of heat or chemical process, as a steam boiler, gas retort etc. 

  • One of the lines of a ruled surface; more generally, an element of some family of linear spaces. 

  • A subordinate piece of code which, given some initial parameters, will generate multiple output values on request. 

  • A piece of apparatus, equipment, etc, to convert or change energy from one form to another. 

  • The principal sound or sounds by which others are produced; the fundamental note or root of the common chord; -- see also generating tone. 

  • Especially, a machine that converts mechanical energy into electrical energy. 

  • An element of a group that is used in the presentation of the group: one of the elements from which the others can be inferred with the given relators. 

piston

noun
  • A solid disk or cylinder that fits inside a hollow cylinder, and moves under pressure (as in an engine) or displaces fluid (as in a pump) 

  • A valve device in some brass instruments for changing the pitch 

verb
  • To move up and down or in and out like a piston. 

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