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English definition of “fly-by-night”

fly-by-night

adjective [not gradable]  /ˈflɑɪ·bɑɪˌnɑɪt/ disapproving us  
(esp. of a business) not able to be trusted, and likely to stop operating without any notice: a fly-by-night operation
(Definition of fly-by-night from the Cambridge Academic Content Dictionary © Cambridge University Press)
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