We found 31 dictionaries that define the word Mayday:

General (23 matching dictionaries)

1. mayday: Longman Dictionary of Contemporary English
2. Mayday: Merriam-Webster
3. Mayday, mayday: Oxford Learner's Dictionaries
4. mayday: American Heritage Dictionary of the English Language
5. Mayday: Collins English Dictionary
6. Mayday: Vocabulary.com
7. Mayday, mayday: Wordnik
8. mayday: Cambridge Advanced Learner's Dictionary
9. Mayday: Webster's New World College Dictionary, 4th Ed.
10. Mayday: The Wordsmyth English Dictionary-Thesaurus
11. mayday: Dictionary.com
12. mayday: Online Etymology Dictionary
13. mayday: Cambridge Essential American English Dictionary
14. MAYDAY, MayDay, Mayday (American band), Mayday (April song), Mayday (Boys Noize album), Mayday (British TV series), Mayday (Cam song), Mayday (Canadian TV series), Mayday (Hugh Cornwell album), Mayday (King Cobb Steelie album), Mayday (Lecrae song), Mayday (Mark Seymour album), Mayday (TV series), Mayday (Taiwanese band), Mayday (Troop album), Mayday (UK TV series), Mayday (disambiguation), Mayday (distress signal), Mayday (film), Mayday (game), Mayday (music), Mayday (music festival), Mayday (novel), Mayday (upcoming film), Mayday: Wikipedia, the Free Encyclopedia
15. Mayday: Rhymezone
16. mayday: FreeDictionary.org
17. mayday: Mnemonic Dictionary
18. Mayday: The Word Detective
19. mayday: TheFreeDictionary.com
20. Mayday: Merriam-Webster
21. Mayday: Wiktionary

Business (1 matching dictionary)

22. Travel Industry Dictionary (No longer online)

Computing (1 matching dictionary)

23. Mayday: Encyclopedia

Miscellaneous (1 matching dictionary)

24. MAYDAY: Acronym Finder

Sports (1 matching dictionary)

25. Mayday: Sports Definitions

Tech (4 matching dictionaries)

26. DOD Dictionary of Military Terms (No longer online)
27. mayday: Chapters in the Sky
28. SeaTalk Dictionary of English Nautical Language (No longer online)
29. MAYDAY, MAYDAY: Latitude Mexico

(Note: See maydays as well.)

Definitions from Wiktionary (Mayday) ▸ noun:  An international distress signal used by shipping and aircraft. ▸ noun:  Alternative form of mayday [An international distress signal used by shipping and aircraft.] Similar: M-day, NOTMAR, Mar., MARPOL, maying, jury mast, marconi, cardinal mark, jurymast, maroon, more... Opposite: mayday call, distress call Phrases: Mayday Parade, Members of Mayday, more... Adjectives: spoken, old, first, blessed, english, foot ▸ Word origin ▸ Words similar to Mayday ▸ Usage examples for Mayday ▸ Idioms related to Mayday ▸ Wikipedia articles (New!) ▸ Popular adjectives describing Mayday ▸ Words that often appear near Mayday ▸ Rhymes of Mayday ▸ Invented words related to Mayday