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

There are more than 2,400 species of fireflies in the United States. —Elliott Harrell, Travel + Leisure, 13 May 2025

This is a powerful tool for firefly conservation efforts. —Owen Martin, The Conversation, 1 May 2025

The Fireflies Put On a Spectacular Show Fireflies are a delight throughout summer in the Southern Appalachians and beyond, but a species of synchronous fireflies found inside the park puts on a choreographed light show every June. —Graham Averill, Outside Online, 25 Apr. 2025

Compared to the more common white or yellow flashes from other species, blue ghost fireflies fly low to the forest floor with a steady light. —Meghan Overdeep, Southern Living, 13 Apr. 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