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

Light pollution and habitat destruction are among the risks facing fireflies. — Eva Flowe july 7, Charlotte Observer, 7 July 2026

Although this is likely an underestimate, due to insufficient data on more than half of North America's firefly species, at least 18 species are officially listed by the International Union for Conservation of Nature as threatened with extinction. — Janet Loehrke, USA Today, 5 July 2026

But stars aren’t the only things that fail to show up when the sky is polluted with light; fireflies, those flashing, nostalgic symbols of summer, often skip the party too. — Evie Carrick, Travel + Leisure, 1 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