/fluy"buy nuyt'/ , 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-nighter .
3. a person or thing that is unreliable, esp. a debtor who evades or attempts to evade creditors.
4. a person regarded as a poor credit risk.
[ 1790-1800 ]