ETT
- Caspar Ett
- EBR ETT
- Elementary Teachers of Toronto
- Embedded Training Teams
- Endotracheal tube
- English Touring Theatre
- English Toy Terrier
- Epithelioid trophoblastic tumour
- Ergothioneine transporter
- Etruscan language
- Euler tour technique
- European Transactions on Telecommunications
- Evacuated Tube Transport
- Exercise Tolerance Test
- Extensional type theory