A creature which flies at night; a nocturnal flier or traveler. / (often attributive) One who departs or flees at night in order to avoid creditors, law enforcement etc.

plural of fly-by-night

(aviation) A system that replaces the conventional manual flight controls of an aircraft with an electronic interface, especially on airliners.

A method of employing people in remote areas by flying them temporarily to the work site instead of permanently relocating them.

(especially Australia) A doctor who uses a light aircraft to visit patients, especially in remote and sparsely inhabited regions.

(nautical folklore) A mythical Dutch-flagged ghost clipper that is very fast sailing, and never makes it to port, seen on the high seas, where upon being hailed, occupants request information on persons long dead, or leave messages for said people. In European naval folklore, it was considered to portend bad luck.

A ship similar to the Flying Dutchman; a ghost ship.

(baseball) A sacrifice fly, a fly out which allows a runner to advance a base.

(nautical) The foremost of the jibs of a square-rigged sailing vessel.

A species of biting horsefly, found around southern Africa, Tabanus biguttatus.