Simple Definition of firefly

from our Learner's Dictionary

firefly

noun

ˈfajɚˌflaɪ

plural fireflies

: a small flying insect that produces a soft light

called also (US) lightning bug

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“Firefly.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/firefly. Accessed 22 Jun. 2026.

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