Definition of "ET"
ET
noun
countable and uncountable, plural ETs
(countable) Abbreviation of extraterrestrial.
(music, countable) Initialism of escape tone.
(physics, uncountable) Initialism of electron tunneling.
(medicine) Initialism of essential tremor.
(medicine) Abbreviation of endotracheal or endotracheal tube.
(travel, aviation) Initialism of electronic ticket.
(travel, aviation, reservation system) End transaction, end of transaction (with transaction meaning an amendment in the reservation system in this sense).