Flier /(flī"ẽr)/ Fli·er Flier n. One who flies or flees; a runaway; a fugitive. A fly. See Fly, n., 9, and 13 (b). (Mach.) See Flyer, n., 5. (Spinning) See Flyer, n., 4. (Arch.) An aëroplane or flying machine.