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firefly

American  
[fahyuhr-flahy] / ˈfaɪərˌflaɪ /

noun

plural

fireflies

  1. any nocturnal beetle of the family Lampyridae, characterized by a soft body with a light-producing organ at the rear of the abdomen.

firefly British  
/ ˈfaɪəˌflaɪ /

noun

  1. any nocturnal beetle of the family Lampyridae , common in warm and tropical regions, having luminescent abdominal organs See 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

Etymology

Origin of firefly

First recorded in 1650–60; fire + fly 1

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.