noun
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.
(idiomatic, derogatory) A person or business that appears and/or disappears rapidly, appearing untrustworthy, or giving an impression of transience.
(idiomatic, derogatory) A traveling businessman or tradesman.