firefly

noun

fire·​fly ˈfī(-ə)r-ˌflī How to pronounce firefly (audio)
: 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

Illustration of firefly

Examples of firefly in a Sentence

Recent Examples on the Web
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Karl Leitz Japan’s Firefly Squid Is Embraced by Chefs Stateside Editors’ Picks Image Each spring, hotaru ika, or firefly squid, ascend to the surface of western Japan’s Toyama Bay to spawn, setting the water aglow with pinpricks of electric blue light. New York Times, 19 Feb. 2025 Congaree National Park See synchronous fireflies put on a limited-time performance Kingville, South Carolina Each spring, this park’s resident fireflies create a magnificent display deep in its dense hardwood forest. Lisa Cericola, Southern Living, 15 Jan. 2025 Late March-early April: Enter the lottery for a ticket to visit nearby Congaree National Park in South Carolina during its immensely popular synchronous fireflies viewing event in May-June. Heidi Finley, Charlotte Observer, 9 Jan. 2025 In the script, there’s no mention of fireflies in that section. Rebecca Alter, Vulture, 25 Dec. 2024 See all Example Sentences for firefly 

Word History

First Known Use

1655, in the meaning defined above

Time Traveler
The first known use of firefly was in 1655

Dictionary Entries Near firefly

Cite this Entry

“Firefly.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/firefly. Accessed 23 Feb. 2025.

Kids Definition

firefly

noun
fire·​fly ˈfī(ə)r-ˌflī How to pronounce firefly (audio)
: any of numerous night-flying beetles that produce a bright soft flashing light for courtship purposes

More from Merriam-Webster on firefly

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