A simple type of jet engine; must be launched at high speed WordNet 3.0 & Open English WordNet

A ramjet is a form of airbreathing jet engine that uses the forward motion of the engine to take in air for combustion that produces jet thrust. Wikipedia

Airbreathing jet engine that uses the engine's forward motion to compress incoming air. Wikipedia Disambiguation

Jet engine that uses the engine's forward motion to compress incoming air Wikidata

A jet engine in which forward motion forces air into an inlet, compressing it, and where combustion is subsonic. OmegaWiki

A simple jet engine consisting essentially of a tube with a means of delivering fuel and ignition into the tube. The engine can only be started in a fast airflow. This type of engine is expected to be able to provide cruising speeds at Mach numbers of around 5 to 7 (5 to 7 times the speed of sound). Wiktionary

A jet engine in which forward motion forces air into an inlet, compressing it (as opposed to having a pump type device compressing the air for combustion with fuel), and where combustion is subsonic. Wiktionary

Ramjet engine. Wiktionary (translation)