firefly

noun

fire·​fly ˈfī(-ə)r-ˌflī 

: any of various winged nocturnal beetles (especially family Lampyridae) that produce a bright soft intermittent light by oxidation of luciferin especially for courtship purposes

Illustration of firefly

Examples of firefly in a Sentence

Recent Examples on the Web

North Carolina is also home to synchronous fireflies, another bioluminescent species that lights up on land. — Charlotte Observer, 12 Aug. 2026

The menu might include ingredients like barracuda wrapped in seaweed, bioluminescent firefly squid, or Wagyu beef, a nod to the region but sourced in Japan. — Erika Ebsworth-Goold, Midwest Living, 3 Aug. 2026

As a just-enjoy-the-firefly-without-trying-to-capture-it-for-Instagram deal. — Steven Zeitchik, HollywoodReporter, 28 July 2026

Keeping Lights on All Night Fireflies need plenty of dark to put on their nocturnal light show and attract the mates needed to produce the next generation of fireflies. — Lauren Landers, Better Homes & Gardens, 17 July 2026

Word History

First Known Use

1655, in the meaning defined above

Rhymes for firefly

• abscissae
• adonai
• alibi
• alkali
• alumni
• amoebae
• amplify
• annuli
• beautify
• brachii
• butterfly
• calculi

Kids Definition

firefly

noun

fire·​fly ˈfī(ə)r-ˌflī 

: any of numerous night-flying beetles that produce a bright soft flashing light for courtship purposes