We found 20 dictionaries that define the word twenty-one:

General (16 matching dictionaries)

1. twenty-one: Oxford Learner's Dictionaries
2. twenty-one: American Heritage Dictionary of the English Language
3. twenty-one, twenty-one: Collins English Dictionary
4. twenty-one: Vocabulary.com
5. Twenty-One, Twenty-one, twenty-one: Wordnik
6. twenty-one: Wiktionary
7. twenty-one: Webster's New World College Dictionary, 4th Ed.
8. twenty-one: The Wordsmyth English Dictionary-Thesaurus
9. twenty-one: Infoplease Dictionary
10. twenty-one: Dictionary.com
11. Twenty-One, Twenty-one: Wikipedia, the Free Encyclopedia
12. twenty-one: Rhymezone
13. twenty-one: FreeDictionary.org
14. twenty-one: Mnemonic Dictionary
15. twenty-one: TheFreeDictionary.com
16. twenty-one: Merriam-Webster

Business (1 matching dictionary)

17. twenty-one: Legal dictionary

Computing (1 matching dictionary)

18. twenty-one: Encyclopedia

Slang (1 matching dictionary)

19. twenty-one: Urban Dictionary

Sports (1 matching dictionary)

20. Twenty-One: Card Games

Definitions from Wiktionary (twenty-one) ▸ noun:  (card games) Blackjack. ▸ noun:  (sports) A basketball-based game in which players attempt to score exactly twenty-one points. Similar: blackjack, vingt-et-un, cardinal, 21, xxi, stiff, vingty, soft hand, belote, pontoon, more... Opposite: negative one, twenty-two Types: blackjack, pontoon, Spanish 21, switch, super fun 21, progressive 21, face up 21, perfect pairs 21, more... Phrases: Twenty-One Demands, Twenty-Five Twenty-One, The Twenty-One Balloons, Twenty-One Card Trick, more... ▸ Words similar to twenty-one ▸ Usage examples for twenty-one ▸ Idioms related to twenty-one ▸ Wikipedia articles (New!) ▸ Popular adjectives describing twenty-one ▸ Words that often appear near twenty-one ▸ Rhymes of twenty-one ▸ Invented words related to twenty-one