Invented by Byzantines, Greek fire was a fearsome weapon. It had the ability to keep burning while on water. As such, it was often used in naval battles. The creation of it was a closely guarded secret and has now been lost.
The term "Greek fire" is normally used in English. However, most other languages use other terms such as "sea fire" (Greek: πῦρ θαλάσσιον), "Roman fire" (πῦρ ῥωμαϊκόν), "war fire" (πολεμικὸν πῦρ), "liquid fire" (ὑγρὸν πῦρ), or "processed fire" (πῦρ σκευαστόν).