I. ˈflībəˌnīt, usu -nīd.+V noun
1. : one given to being abroad at night
2. also fly-by-night·er |flībə|nīd.ə(r), -nītə-
a. : one that escapes at night from his creditors
b. : one without established reputation or standing and therefore regarded as a poor risk (as for credit or future productivity)
3. : a square sail sometimes spread on fore-and-aft-rigged ships when running before the wind
II. adjective
1. of a business enterprise or promoter : established or prepared to take advantage of an opportunity for immediate profit and often shady or irresponsible and inadequately financed for stability
a fly-by-night salesman
fly-by-night insurance plans
a fly-by-night cut-rate drugstore
2. : transitory , passing
a fly-by-night political disorder
: unreliable , unstable
the symphony was no fly-by-night venture — Green Peyton