We found 25 dictionaries that define the word so long:

General (21 matching dictionaries)

1. so long: Longman Dictionary of Contemporary English
2. so long: Merriam-Webster
3. so long: Oxford Learner's Dictionaries
4. so long: American Heritage Dictionary of the English Language
5. so long: Collins English Dictionary
6. so long: Vocabulary.com
7. So-long, so-long: Wordnik
8. so long: Cambridge Advanced Learner's Dictionary
9. so long: Wiktionary
10. so long: The Wordsmyth English Dictionary-Thesaurus
11. so long: Infoplease Dictionary
12. so long, so long: Dictionary.com
13. so long: Online Etymology Dictionary
14. So Long (ABBA song), So Long (Diplo song), So Long (Russ Morgan song), So Long (song): Wikipedia, the Free Encyclopedia
15. so long: Rhymezone
16. so long: FreeDictionary.org
17. so long: Mnemonic Dictionary
18. so long: TheFreeDictionary.com
19. so-long: Wikimedia Commons US English Pronunciations

Computing (1 matching dictionary)

20. so long: Encyclopedia

Miscellaneous (1 matching dictionary)

21. so long: Idioms

Slang (2 matching dictionaries)

22. so long: Green’s Dictionary of Slang
23. so long: Urban Dictionary

(Note: See so_longs as well.)

Definitions from WordNet (so long) ▸ noun:  a farewell remark Opposite: hello, hi, greetings, hey Phrases: so long as, as so long as, Not So Long Ago, So Long a Letter, So Long and Thanks for All the Shoes, more... ▸ Word origin ▸ Words similar to so long ▸ Usage examples for so long ▸ Idioms related to so long ▸ Wikipedia articles (New!) ▸ Words that often appear near so long ▸ Rhymes of so long ▸ Invented words related to so long