Unzipping the Origins of 'Fly'

Rob Kyff on

Why is the zippered opening on a pair of pants called a "fly"?

Before you start speculating about body parts lurking near the fly or bodily functions occurring though it, you'll be glad to know that the origin of this "fly" has nothing to do with anatomy.

"Fly" has long meant "to travel through the air," so certain objects that do so, such as winged insects or soaring baseballs, came to be called "flies."

"Fly" was also applied to a piece of material that flies out, flag-like, from an attachment at one end. The "fly" on a tent, for instance, refers to the material that covers its entrance or that sails above it as an outer roof. Soon the word "fly" also attached itself to the small flap of fabric that "flies out" over a zipper to conceal it.

Now that we've sewn up that flap, let's fly to the origins of...

--Fly by night -- Over the centuries, English speakers have applied this term to several different phenomena.

During the 1700s, a "fly-by-night" was a reproachful term for an old woman, implying that she was a witch who flew on a broomstick at night. A century later, it referred to a Victorian-era version of Uber -- a light, two-wheeled carriage that flew through London's streets at night.

But our current use of the adjective "fly-by-night" to refer to an unreliable or untrustworthy business or operation arose during the early 1800s. It described unscrupulous tenants who attempted to beat the rent by fleeing their lodgings at night and disappearing forever.

--Fly (adjective) -- This term meaning "sharp, alert, with it," first appeared in American slang 200 years ago and was widely popularized by African-American and hip-hop culture during the 1970s and 1980s, as in the movie "Super Fly."

Some say "fly" derives from the wily vigilance of the housefly. Others swat that theory, claiming it comes from "fla," an abbreviation of "flash" used in 19th-century slang to mean "clever."

--Flying colors -- If a 17th-century naval vessel emerged victorious from a battle with all its ensigns (colors) still flying, this usually meant that it had suffered little damage. So such a ship was said to have "come off with flying colors." Later on, "pass with flying colors" became a general term meaning "to succeed or win by a wide margin."

I wonder whether abstract expressionist Jackson Pollack, known for throwing paint at the canvas, passed his art school courses with flying colors.


Rob Kyff, a teacher and writer in West Hartford, Conn., invites your language sightings. Send your reports of misuse and abuse, as well as examples of good writing, via e-mail to or by regular mail to Rob Kyff, Creators Syndicate, 737 3rd Street, Hermosa Beach, CA 90254.

Copyright 2017 Creators Syndicate Inc.

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