Ett or ETT may refer to: Arts Caspar Ett (1788–1847), German composer and organist English Touring Theatre
Mathematics Euler tour technique, in graph theory Extensional type theory, in logic
Medicine Endotracheal tube, in respiratory medicine Epithelioid trophoblastic tumour, a very rare cancer Ergothioneine transporter, a protein and human gene (SLC22A4) Exercise Tolerance Test, in cardiology
Military Embedded Training Teams in Afghanistan EBR ETT, a French armoured personnel carrier
Other uses Elementary Teachers of Toronto, a Canadian labour union English Toy Terrier, a dog breed Etruscan language, once spoken in Italy (ISO 639-3: ett) European Transactions on Telecommunications, a scientific journal Evacuated Tube Transport