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

Bulb size and shape Fairy lights are iconic for their tiny lights that give off a glow similar to fireflies on a warm summer evening. —Bestreviews, Chicago Tribune, 27 May 2025

Goree remembers her town through images of crickets singing and fireflies lighting up the night sky. —Ignacio Calderon, USA Today, 23 May 2025

Held in the heart of the Allegheny National Forest, these gatherings are part fundraiser, part firefly conservation event (and fully magical to boot). —Allison Palmer, Sacbee.com, 21 May 2025

Guests will look for fireflies and participate in glow-in-the-dark activities from 6 to 8 p.m. Friday, June 6. —Monica Hooper, Arkansas Online, 17 May 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