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

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Etymology

Origin of firefly

First recorded in 1650–60; fire + fly ¹

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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

And then a single firefly flies out over the house, which is lovely.

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

The stores are your go-to for Tiana-themed plushies, headgear and toys, including an interactive and wearable light-up firefly.

From Los Angeles Times ● Nov. 14, 2024

Everyone in the courtyard seemed to be holding their breath, A pinprick of light appeared in the Governor's palm, like a hovering firefly.

From "A Wish in the Dark" by Christina Soontornvat

One was so dim that detecting it would be comparable to standing on Earth and spotting a small swarm of fireflies on the Moon.

From Science Daily ● Nov. 2, 2026

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

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

For a second I thought it might be Pita looking for fireflies, but she was standing at the cake table, digging into her second helping.

From "Summer of the Mariposas" by Guadalupe García McCall

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