We found 30 dictionaries that define the word firefly:

General (25 matching dictionaries)

1. firefly: Merriam-Webster
2. firefly, firefly: Oxford Learner's Dictionaries
3. firefly: American Heritage Dictionary of the English Language
4. firefly: Collins English Dictionary
5. firefly: Vocabulary.com
6. Firefly, firefly: Wordnik
7. firefly: Cambridge Advanced Learner's Dictionary
8. firefly: Wiktionary
9. firefly: Webster's New World College Dictionary, 4th Ed.
10. firefly: The Wordsmyth English Dictionary-Thesaurus
11. firefly: Infoplease Dictionary
12. Firefly, firefly: Dictionary.com
13. firefly: Cambridge Essential American English Dictionary
14. FIREFLY, FireFly (song), Firefly (Archie Comics), Firefly (Boom! Studios comics), Firefly (DC Comics), Firefly (Emily Remler album), Firefly (G.I. Joe), Firefly (Jeremy Steig album), Firefly (Metaxa song), Firefly (TNT album), Firefly (TV Series), Firefly (TV series), Firefly (The Batman), Firefly (Uriah Heep album), Firefly (airline), Firefly (band), Firefly (cache coherence protocol), Firefly (car rental), Firefly (comics), Firefly (computer), Firefly (computer program), Firefly (dinghy), Firefly (disambiguation), Firefly (film), Firefly (film series), Firefly (franchise), Firefly (key exchange protocol), Firefly (mobile phone), Firefly (protocol), Firefly (series), Firefly (television), Firefly (television series), Firefly (train), Firefly (tv series), Firefly (website), Firefly, The Firefly (Fringe), The Firefly (film), The Firefly (operetta): Wikipedia, the Free Encyclopedia
15. Firefly: Online Plain Text English Dictionary
16. firefly: Webster's Revised Unabridged, 1913 Edition
17. firefly: Rhymezone
18. Firefly: AllWords.com Multi-Lingual Dictionary
19. firefly: Webster's 1828 Dictionary
20. firefly: FreeDictionary.org
21. firefly: Mnemonic Dictionary
22. firefly: TheFreeDictionary.com
23. firefly: Longman Dictionary of Contemporary English

Computing (1 matching dictionary)

24. firefly: Encyclopedia

Medicine (1 matching dictionary)

25. online medical dictionary (No longer online)

Miscellaneous (1 matching dictionary)

26. Brilliant Dream Dictionary (No longer online)

Science (1 matching dictionary)

27. firefly: LITTLE EXPLORERS(TM) Picture Dictionary

Tech (1 matching dictionary)

28. Rane Professional Audio Reference (No longer online)

(Note: See fireflies as well.)

Definitions from Wiktionary ( ) ▸ noun:  (Northern US, Western US, Florida) Any beetle of the family Lampyridae, which exhibit bioluminescence during twilight. Similar: fire beetle, lightning bug, pyrophorus noctiluca, fire-fly, lampyrid, lampyrine, lanternfly, firebeetle, glow fly, common glowworm, more... Opposite: lightning bug Types: western firefly, synchronous firefly, pyralis firefly, elliptical firefly, fungus gnat, more... Phrases: Firefly luciferase, Firefly luciferin, Firefly squid, firefly luciferases, luciferases, firefly, more... Adjectives: little, first, female, single, common, big, giant, solitary, american, tiny, poor Colors:     lime,     neon green,     electric blue,     bright yellow,     luminous white, more... ▸ Words similar to firefly ▸ Usage examples for firefly ▸ Idioms related to firefly ▸ Wikipedia articles (New!) ▸ Popular adjectives describing firefly ▸ Words that often appear near firefly ▸ Rhymes of firefly ▸ Invented words related to firefly