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

Rangers lead synchronous firefly viewing tours in the late summer to help travelers safely watch as nature’s magic unfolds. —Stephanie Vermillion, Travel + Leisure, 9 May 2026

You won't be allowed to catch fireflies, use bug spray, or take cell phone photos during the event. —Brandee Gruener, Southern Living, 9 Apr. 2026

People invented many strange and creative light sources to fend off the night: campfires, capturing fireflies in a lantern, making candles from salmon or cow fat, or even, according to some sailors’ accounts, pushing a wick inside an oily seabird and lighting it. —Literary Hub, 8 Apr. 2026

All along the far side of the canyon, a cluster of dots began to wink on, like fireflies cavorting in a field. —New York Times, 16 Mar. 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