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[flahy-bahy-nahyt] /ˈflaɪ baɪˌnaɪt/
not reliable or responsible, especially in business; untrustworthy:
a fly-by-night operation.
not lasting; brief; impermanent; transitory:
a fly-by-night theater.
noun, Also, fly-by-nighter
a person or thing that is unreliable, especially a debtor who evades or attempts to evade creditors.
a person regarded as a poor credit risk.
Origin of fly-by-night
First recorded in 1790-1800 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for fly-by-night
Contemporary Examples
Historical Examples
  • She certainly has acted like a fly-by-night up to this time.

    They of the High Trails

    Hamlin Garland
  • He'll be out with a fly-by-night troupe afore the next month.

    Watch Yourself Go By Al. G. Field
  • Shown up in our newspapers as a ditch-digger—a fly-by-night—a nobody!

    The Landloper Holman Day
  • Had the wind been directly astern, the course of the fly-by-night would have been smoother.

    Janice Day Helen Beecher Long
  • Torched on by that fly-by-night who'll be getting out of town and who'll be forgotten inside a week.

  • What gets me is, when you boil our two fly-by-night stories down, I've come here to be alone.

    Seven Keys to Baldpate Earl Derr Biggers
  • Does any one figger I'll allow some fly-by-night charl'tan to go reeflectin' on me?

    Faro Nell and Her Friends Alfred Henry Lewis
  • She now knew where she was, but was nearly dying from the exhaustion of his fly-by-night expeditions.

    Crooked Trails Frederic Remington
British Dictionary definitions for fly-by-night


unreliable or untrustworthy, esp in finance
brief; impermanent
an untrustworthy person, esp one who departs secretly or by night to avoid paying debts
a person who goes out at night to places of entertainment
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for fly-by-night

1796, slang, said to be an old term of reproach to a woman signifying that she was a witch; extended 1823 to "anyone who departs hastily from a recent activity," especially while owing money. The two senses involve the two verbs fly.

Online Etymology Dictionary, © 2010 Douglas Harper
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fly-by-night in Culture

fly-by-night definition

Shady or untrustworthy: “Before buying stock in a newly formed company, the prudent investor will check its owners' credentials to make sure it's not a fly-by-night operation.”

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Slang definitions & phrases for fly-by-night



Undependable and dishonest: fly-bynight correspondence school

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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