FLT can refer to:
- Fairlight (group), a warez release group
- Federación Libre de Trabajadores (Free Federation of Workers), Puerto Rico
- Fédération Luxembourgeoise de Tennis (Luxembourg Tennis Federation)
- First Law of Thermodynamics
- Finger Lakes Trail, system of hiking trails in New York, US
- flt., wind instrument technique of flutter-tonguing
- Front de Libération du Tchad or Liberation Front of Chad
- Fermat's little theorem, that $a^p \equiv a \pmod p$ for a prime number p and any whole number a
- Fermat's last theorem, that the equation a + b = c has no solution in whole numbers, for n ≥ 3
- [F] 3'-fluoro-3'-deoxythymidine, a PET tracer used for medical imaging
- Football League Trophy, an annual English association football knock-out competition
- Forklift Truck, a vehicle for lifting pallets in warehouses and transport hubs
Usage examples of "flt".
On our arrival in Scarborough we had a talk from our Flight Commander, Flt. Lieut.
I felt my rigid lips creak apart, and my head tilt back to aim at what I took to be Flt. Lieut.