How to say "engine" in Japanese

• エンジンJLPT N3approx.Common
  nounThe everyday loanword for an engine: the engine of a car, aircraft, boat or machine. This is the word you want in almost any ordinary context, from mechanical talk to chat about a car.
  そのエンジンは蒸気じょうきで動うごく。↗

  The engine is driven by steam.
• 機関きかんJLPT N3approx.Common
  nounA formal word for an engine; in everyday contexts エンジン is the usual choice, and 機関 appears mainly in technical and railway vocabulary, as in the set term 機関車.
• モーターJLPT N2approx.Common
  nounReally means 'motor', especially an electric motor; the 'engine' gloss reflects loose everyday usage. For a car or aircraft engine, エンジン is the word you want, not モーター.
  そのボートは動力どうりょくにモーターを使用しようしている。↗

  The boat uses a motor for the power.
• 機関車きかんしゃJLPT N2approx.Common
  nounSpecifically a locomotive: the self-powered vehicle that pulls a train. Use it only for this railway sense of 'engine'; it is not a word for car or aircraft engines.
  機関車きかんしゃは長ながい貨物車かもつしゃの列れつを引っ張ひっぱって走はしっていた。↗

  The locomotive was pulling a long line of freight cars.

Choose 「エンジン」 for the engine of a car, aircraft or machine; 機関 is the formal counterpart, known chiefly from railway terms such as 機関車; 「モーター」 is really 'motor'; 機関車 means a locomotive.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• エンジンengine
• 機関きかんengine
• モーターmotor
• 機関車きかんしゃlocomotive
• エンジン発動機エンジンはつどうきengine
• 発動機はつどうきengine