A fly-by-night is defined as an unreliable person who is generally not known and who cannot be trusted.(noun)
An example of a fly-by-night is a contractor who takes your money to produce your kitchen cabinets and then never produces them.
The definition of a fly-by-night is an unreliable person who is generally not known and who cannot be trusted.(adjective)
An example of fly-by-night person is the description used for a salesman who promises the world but doesn't deliver.
See fly-by-night in Webster's New World College Dictionary
See fly-by-night in American Heritage Dictionary 4
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