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

The beneficial insects, like butterflies, moths, fireflies, and native bees, that pollinate your garden throughout the growing season require leaf litter to survive. —Mary Marlowe Leverette, Southern Living, 4 Oct. 2025

There were fireflies everywhere. —Tomás Mier, Rolling Stone, 3 Oct. 2025

Wildlife habitats are certified by the National Wildlife Federation, firefly habitats are certified by Firefly Conservation and Research, and hummingbird havens are certified by the International Hummingbird Society. —Caitlin Looby, jsonline.com, 25 Sep. 2025

In a breeze, the solar lights sway softly, flickering like fireflies. —Nora Colomer May Earn A Commission If You Buy Through Our Referral Links. This Content Was Created By A Team That Works Independently From The Fox Newsroom., FOXNews.com, 8 Sep. 2025

Word History

First Known Use

1655, in the meaning defined above

Rhymes for firefly

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

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