firefly

American  

[fahyuhr-flahy] / ˈfaɪərˌflaɪ /

noun

• fireflies
  plural

1. any nocturnal beetle of the family Lampyridae, characterized by a soft body with a light-producing organ at the rear of the abdomen.

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firefly British  

/ ˈfaɪəˌflaɪ /

noun

1. any nocturnal beetle of the family Lampyridae , common in warm and tropical regions, having luminescent abdominal organs See also glow-worm

2. any tropical American click beetle of the genus Pyrophorus , esp P. noctiluca , that have luminescent thoracic organs

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Other Word Forms

Noun Inflected Forms

• fireflies
  plural

Etymology

Origin of firefly

First recorded in 1650–60; fire + fly ¹

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

See Examples For:

firefly fireflies

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

There was such a discussion about how a firefly flashes — How many seconds?

From Los Angeles Times ● Mar. 27, 2025

Scribner: We have over 50 automated elements, including the turntable, lifts, firefly hatches in the deck — they’re individually programmable pieces, but they’re run by operators who press buttons rhythmically and in the right order.

From Los Angeles Times ● Mar. 27, 2025

“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

“Interrogation Room One. Interrogation Room Two. Isolation Room One,” she whispered, her flashlight flickering across the words like an anxious firefly.

From "Uglies" by Scott Westerfeld

"We live practically like fireflies here -- in the dark all the time. You never know when you'll have power; it's our sad reality," Julian Gonzalez, a 72-year-old carpenter, told AFP.

From Barron's ● Aug. 2, 2026

The trick is also shared by certain squid and jellyfish species, as well as insects such as fireflies and glow-worms.

From BBC ● Jun. 25, 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

When they were younger, we did fireworks, BBQ, a summer night alive with fireflies and bullfrogs, all that stuff.

From Salon ● May 31, 2026

There was a soft light coming from fireflies and the bright stars above.

From "The Way to Rio Luna" by Zoraida Cordova