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

Definition of firefly

: 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 But Vaz’s modeling studies point to light pollution as a possible cause for a decline in firefly diversity in Brazil’s Atlantic Forest. Elizabeth Pennisi, Science | AAAS, "Can scientists help insects survive their fatal attraction to light at night?," 4 May 2021 Move over Immersive Van Gogh, Great Smoky Mountains National Park in Tennessee has just announced the dates for its mesmerizing annual firefly show. Meena Thiruvengadam, Travel + Leisure, "The Great Smoky Mountains' Synchronizing Fireflies Are Coming — but You Need to Enter a Lottery to See Them," 29 Apr. 2021 Great Smoky Mountains National Park will once again host its annual synchronous firefly viewing this year, with some changes for pandemic safety. From Usa Today Network And Wire Reports, USA TODAY, "Firefly lottery, vaccine exemptions, data breach: News from around our 50 states," 29 Apr. 2021 Taiwan, for example, is considered an example of sustainable firefly tourism. Ellie Shechet, Popular Science, "Firefly tourism has a surprising dark side," 15 Mar. 2021 During May and June every summer, watch a spectacular firefly synchronization, where hundreds of Phontinus frontalis blink in unison as part of their mating ritual. Sucheta Rawal, Travel + Leisure, "The Best Places to Spot Wildlife in South Carolina," 26 Feb. 2021 Then, with cameras rolling inside the tent, Sarfati and Peleg captured firefly behavior on an individual level within the swarm. Courtney Holden, Smithsonian Magazine, "How Fireflies’ Dramatic Light Show Might Spark Advances in Robot Communication," 27 Oct. 2020 There’s a chance that this sharp decrease in firefly tourism might be good for the beetles. Nora Mcgreevy, Smithsonian Magazine, "Watch Fireflies Flicker From the Comfort of Home," 2 June 2020 But how many people know what puts the fire in the firefly? Jason Bittel, Washington Post, "Fireflies’ glow is thanks to a special lantern," 25 Aug. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'firefly.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of firefly

1655, in the meaning defined above

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Time Traveler for firefly

Time Traveler

The first known use of firefly was in 1655

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Statistics for firefly

Last Updated

9 May 2021

Cite this Entry

“Firefly.” Dictionary, Merriam-Webster, Accessed 10 May. 2021.

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More Definitions for firefly



English Language Learners Definition of firefly

: a small flying insect that produces a soft light


fire·​fly | \ ˈfīr-ˌflī How to pronounce firefly (audio) \
plural fireflies

Kids Definition of firefly

: a small beetle producing a soft light

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More from Merriam-Webster on firefly

Nglish: Translation of firefly for Spanish Speakers

Britannica English: Translation of firefly for Arabic Speakers Encyclopedia article about firefly

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