plural of fly-by-night

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.

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

(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.

plural of fly out

A rapid-response unit of a police force.

plural of fly ball

(baseball) A batted ball which is in play and subject to the infield fly rule.

(derogatory) a rock pigeon, or a seagull, living in an urban environment, especially one regarded as pesky, loud or a scavenger.