compound engine


Definition of compound engine

1 : an engine (as a steam engine) in which the working fluid is expanded successively in two distinct phases so as to minimize losses (as from cylinder condensation) and so allow a high ratio of expansion to be used, the working fluid (as steam) after expanding in the high-pressure cylinder being exhausted into a low-pressure cylinder and then exhausted usually into a condenser
2 aeronautics : a propulsive system consisting essentially of a reciprocating engine, a steady-flow gas turbine, and a compressor so arranged that (1) the exhaust from the reciprocating engine drives the turbine, the exhaust from the turbine being directed rearward for jet propulsion, (2) the turbine drives the compressor, the excess turbine power being delivered to the engine shaft through gearing, and (3) the net shaft power of the system is converted to propulsive power by means of a propeller

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Learn More about compound engine

Statistics for compound engine

Cite this Entry

“Compound engine.” The Dictionary, Merriam-Webster Inc., Accessed 16 December 2019.

Comments on compound engine

What made you want to look up compound engine? Please tell us where you read or heard it (including the quote, if possible).


having a smooth flowing sound

Get Word of the Day daily email!

Test Your Vocabulary

Great Scrabble Words—A Quiz

  • scrabble tiles that read scrabble quiz
  • Which of the following Q-without-U words means the number five in cards or dice?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!