We found 21 dictionaries that define the word all fools' day:

General (20 matching dictionaries)

1. All Fools' Day: Merriam-Webster
2. All Fools' Day: Oxford Learner's Dictionaries
3. All Fools' Day: American Heritage Dictionary of the English Language
4. All Fools' Day, All Fools' Day: Collins English Dictionary
5. All Fools' day: Vocabulary.com
6. All Fools' Day: Wordnik
7. All Fools' Day: Cambridge Advanced Learner's Dictionary
8. All Fools' Day: Wiktionary
9. All Fools' Day: The Wordsmyth English Dictionary-Thesaurus
10. All Fools' Day, all fools' day, all fools day: Dictionary.com
11. All Fools Day (album), All Fool's Day, All Fools' Day, All Fools Day: Wikipedia, the Free Encyclopedia
12. All Fools' Day: Online Plain Text English Dictionary
13. All fools' day: Rhymezone
14. All Fools' Day: AllWords.com Multi-Lingual Dictionary
15. all-fools-day: Webster's 1828 Dictionary
16. all fools day: FreeDictionary.org
17. all fools' day: Mnemonic Dictionary
18. All Fools' Day: TheFreeDictionary.com
19. All Fools Day: Dictionary of Phrase and Fable (1898)
20. all fools day: Longman Dictionary of Contemporary English

Computing (1 matching dictionary)

21. All Fool's Day, All Fools Day, All Fools' day: Encyclopedia

Definitions from Wiktionary (All Fools' Day) ▸ noun:  April 1, a day when practical jokes are traditionally played ▸ Words similar to all fools' day ▸ Usage examples for all fools' day ▸ Idioms related to all fools' day ▸ Wikipedia articles (New!) ▸ Words that often appear near all fools' day ▸ Rhymes of all fools' day ▸ Invented words related to all fools' day