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.

---

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

---

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

The number of applications for parking spots at Great Smoky Mountains National Park during the annual eight-night firefly viewing period.

From The Wall Street Journal ● Jun. 5, 2026

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

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

With the ringed planet in the background, the glow of the ship leaving Sagan bends in an oval like a firefly, until the light is gone.

From "The Last Cuentista" by Donna Barba Higuera

"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

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

From Salon ● May 31, 2026

Wildflowers flashed like fireflies in the brooding jungle of “Floral Entrapment II,” which artist Ema Ri made by applying paint with their hands and nails.

From The Wall Street Journal ● Nov. 6, 2025

“You remember the fireflies that like to hang out in my backyard?”

From "Kwame Crashes the Underworld" by Craig Kofi Farmer