We found 30 dictionaries that define the word adieu:

General (26 matching dictionaries)

1. adieu: Merriam-Webster
2. adieu: Oxford Learner's Dictionaries
3. adieu: American Heritage Dictionary of the English Language
4. adieu: Collins English Dictionary
5. adieu: Vocabulary.com
6. Adieu, adieu: Wordnik
7. adieu: Cambridge Advanced Learner's Dictionary
8. adieu: Wiktionary
9. adieu: Webster's New World College Dictionary, 4th Ed.
10. adieu: The Wordsmyth English Dictionary-Thesaurus
11. adieu: Infoplease Dictionary
12. Adieu, adieu: Dictionary.com
13. adieu: Online Etymology Dictionary
14. Adieu (Stockhausen), Adieu: Wikipedia, the Free Encyclopedia
15. Adieu: Online Plain Text English Dictionary
16. adieu: Webster's Revised Unabridged, 1913 Edition
17. adieu: Rhymezone
18. Adieu, adieu, adieu (m): AllWords.com Multi-Lingual Dictionary
19. adieu: Webster's 1828 Dictionary
20. adieu: FreeDictionary.org
21. adieu: Mnemonic Dictionary
22. adieu: TheFreeDictionary.com
23. adieu: Longman Dictionary of Contemporary English
24. adieu: Merriam-Webster

Computing (1 matching dictionary)

25. adieu: Encyclopedia

Miscellaneous (2 matching dictionaries)

26. Brilliant Dream Dictionary (No longer online)
27. adieu: Idioms

Slang (1 matching dictionary)

28. Adieu: Urban Dictionary

(Note: See adieus as well.)

Definitions from Wiktionary ( ) ▸ noun:  A farewell, a goodbye; especially a fond farewell, or a lasting or permanent farewell. Similar: bye-bye, adios, good-bye, sayonara, goodbye, arrivederci, bye, cheerio, Goodby, au revoir, more... Opposite: hello, goodbye Types: bye, goodbye, farewell, adios, aloha, more... Phrases: I Do, Adieu, Comment te dire adieu, Adieu l'ami, The Ladies of Grace Adieu and Other Stories, bid adieu, more... Adjectives: last, final, bade, long, eternal, more, affectionate, fond, sad, hasty, silent Colors:     sunset orange,     midnight blue,     dusky rose,     dusk gray, more... ▸ Word origin ▸ Words similar to adieu ▸ Usage examples for adieu ▸ Idioms related to adieu ▸ Wikipedia articles (New!) ▸ Popular adjectives describing adieu ▸ Words that often appear near adieu ▸ Rhymes of adieu ▸ Invented words related to adieu