[fahyuh r-flahy]
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noun, plural fire·flies.
  1. any nocturnal beetle of the family Lampyridae, characterized by a soft body with a light-producing organ at the rear of the abdomen.
Compare glowworm.

Origin of firefly

First recorded in 1650–60; fire + fly2
Also called glowfly, lightning bug. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for firefly

firefly, fireworm, glowworm, lampyrid, noctiluca

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British Dictionary definitions for firefly


noun plural -flies
  1. any nocturnal beetle of the family Lampyridae, common in warm and tropical regions, having luminescent abdominal organsSee also glow-worm
  2. any tropical American click beetle of the genus Pyrophorus, esp P. noctiluca, that have luminescent thoracic organs
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for firefly

1650s, from fire (n.) + fly (n.).

Online Etymology Dictionary, © 2010 Douglas Harper