The condition jetlag is first attested in a 1965 newspaper article. Before that, people called it time zone syndrome. The first regular jetliner service began in 1958, the airplane type named for the turbojet engines that made them possible. Boeing inaugurated the jetliner naming scheme they still use today with the 707. Planes powered by turbojet engines first flew in 1944, marking a 14-year timespan from first deployment to consumer availability.

A jet engine is an engine that generates thrust by expelling a jet of fast moving fluid opposite the direction of movement, propelling the craft forward. This definition technically includes both hydrojet/pumpjet watercraft engines and rocket engines, but “jet engine” typically only refers to aircraft engines. Many marine animals are also jet-propelled, including all jellyfish and octopuses. Before jet engines, powered aircraft flew by using propellers to generate thrust.

Emitted jets of water or air were named in the 1660s through a borrowing from French jet, meaning “a throw”. French jet can be traced back to Old French get, then Vulgar Latin jectus and Classical Latin iactus, all meaning “a throw”. Iactus is a form of iacere, which just means “to throw”. Meanwhile, lag first appears in English in the 1530s with the same meaning as today, and has an uncertain origin. Wisdom teeth were called lag-teeth in the 1610s.