fly-by-night
UK[ˌflaɪ baɪ ˈnaɪt]US[ˌflaɪ baɪ ˈnaɪt]
adj
unreliable and likely to disappear or fail, especially in business or financial matters.
n
a person or company that is unreliable and likely to disappear or fail, especially in business.
Etymology
the term 'fly-by-night' originated in the late 18th century with a literal meaning, describing a person who flees under the cover of darkness to avoid creditors or legal obligations. this imagery of nocturnal escape was a powerful metaphor for unreliability and dishonesty. by the mid-19th century, the term had solidified into its modern figurative sense, primarily used as a pejorative for businesses or individuals who are financially unstable, untrustworthy, and likely to vanish without fulfilling their commitments. its evolution perfectly captures the transition from a concrete description of an action to an abstract characterization of dubious character and practice.
Analysis
this is a compound phrase formed from three english words: 'fly' (from old english 'flēogan', meaning to move through the air), 'by' (from old english 'bī', meaning near or past), and 'night' (from old english 'niht', meaning the period of darkness). the phrase functions as a fixed idiom.
Examples
the neighborhood is full of fly-by-night contractors who take deposits and never return to do the work.
investors were warned to avoid the fly-by-night investment scheme promising unrealistic returns.
we only work with established suppliers, not some fly-by-night operation.