firefly

American  

[fahyuhr-flahy] / ˈfaɪərˌflaɪ /

noun

plural

fireflies

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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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

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

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 study warns against increasing agricultural intensification, especially practices that reduce the organic debris and moist environments firefly larvae require to thrive.

From Science Daily • Apr. 29, 2024

The orb then turns into a firefly, and the insect starts to fly away.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer