firefly
Americannoun
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fireflies
plural
noun
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any nocturnal beetle of the family Lampyridae , common in warm and tropical regions, having luminescent abdominal organs See also glow-worm
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any tropical American click beetle of the genus Pyrophorus , esp P. noctiluca , that have luminescent thoracic organs
Other Word Forms
Noun Inflected Forms
Etymology
Origin of firefly
Explanation
Fireflies are flying beetles that glow in the dark. If you gently catch a firefly between your palms, you can watch its light flicker on and off for a while, and then let it go. Depending on where you live, you may call fireflies "lightning bugs" or "glowworms." There are fewer of these light-emitting insects on the planet than there used to be, but you can still find places where they gather in groups at dusk, glowing and flickering like stars. Contrary to their name, fireflies aren't flies, but instead belong to a family of beetles with an amazing ability to produce a luminous light.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Chief among them is Photinus carolinus, also known as the Smokies synchronous firefly, which produces dazzlingly coordinated displays that rival even the most extravagant Christmas light installation.
From The Wall Street Journal ● Jun. 3, 2026
The Photinus carolinus species of firefly has just a few weeks every summer to flash their bioluminescent lights and mate.
From The Wall Street Journal ● Jun. 3, 2026
“It takes the light coming from the firefly and bends it and amplifies it so we can see it in glorious detail,” he told BBC News.
From BBC ● Dec. 11, 2024
Emotionally, after riding through a cavern featuring a frog-led band with a firefly chorus, all creating a rousing, sing-along take on “Dig a Little Deeper,” the mood is one of pure uplift.
From Los Angeles Times ● Jun. 11, 2024
The end of his cigar glowed brighter when he inhaled, like some fat red firefly.
From "The Evolution of Calpurnia Tate" by Jacqueline Kelly
He has also used the technology for art installations with flexible rods that, when speared into the ground, have tips that glow in the dark like fireflies on tall grass.
From Barron's ● Aug. 5, 2026
Nature-loving travelers from around the globe are bugging out over the fireflies, descending en masse on isolated stretches of the U.S.
From The Wall Street Journal ● Jun. 3, 2026
In a way, all animals make rhythms, whether in the form of fireflies flashing, birds chirping or even a tiger pacing back and forth.
From Salon ● Jun. 7, 2025
A line in “Maybe Happy Ending” describes the lives of fireflies, the once-ubiquitous insects that magically produce their own light.
From Los Angeles Times ● Mar. 27, 2025
The eloko was running too, batting away Koffi’s fireflies as it pursued them.
From "Beasts of Prey" by Ayana Gray
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
