acronym meaning Extended-range Twin-engine OPerationS
Or if you are a passenger airline mechanic: Engines Turn Or People Swim
Or if you are a UPS mechanic: Engines Turn Or Packages Sink
Aircraft and engines get an ETOPS rating which is a certain number of minutes. The number of minutes is how far that aircraft can be from an airport and lose an engine and still make it there easily. Most airplanes that have high ETOPS ratings could fly all day on one engine.
IE: The Boeing 777 has an ETOPS rating of 180 minutes.