Pronunciation: (flī'bī-nīt"),[key] —adj. 1. not reliable or responsible, esp. in business; untrustworthy: a fly-by-night operation. 2. not lasting; brief; impermanent; transitory: a fly-by-night theater.
—n.Also,fly'-by-night'er. 1. a person or thing that is unreliable, esp. a debtor who evades or attempts to evade creditors.
2. a person regarded as a poor credit risk.