Fly-by-night

Meaning

Unreliable, operating only briefly and often dishonestly.

Usage

Warns against temporary, shady businesses.

Origin & History

Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.

People who vanish overnight, like birds of passage.

Earliest recorded in the 18th century.