We found 22 dictionaries that define the word o'clock:

General (19 matching dictionaries)

1. o'clock: Merriam-Webster
2. o'clock: Oxford Learner's Dictionaries
3. o'clock: American Heritage Dictionary of the English Language
4. o'clock, o'clock: Collins English Dictionary
5. o'clock: Vocabulary.com
6. O'Clock, OClock, OClock, O'clock, Oclock, o'clock, oclock, oclock, oClock, o'Clock: Wordnik
7. o'clock: Cambridge Advanced Learner's Dictionary
8. o'clock: Wiktionary
9. o'clock: Webster's New World College Dictionary, 4th Ed.
10. o'clock: The Wordsmyth English Dictionary-Thesaurus
11. o'clock, oclock: Dictionary.com
12. oclock: Cambridge Essential American English Dictionary
13. O'Clock (album), O'clock: Wikipedia, the Free Encyclopedia
14. o'clock: Rhymezone
15. o'clock: AllWords.com Multi-Lingual Dictionary
16. oclock: FreeDictionary.org
17. o'clock: Mnemonic Dictionary
18. o'clock, oclock: TheFreeDictionary.com
19. oclock: Wordnik

Miscellaneous (1 matching dictionary)

20. AbbreviationZ (No longer online)

Science (1 matching dictionary)

21. How Many? A Dictionary of Units of Measurement (No longer online)

Slang (1 matching dictionary)

22. O'clock: Urban Dictionary

Definitions from WordNet (o'clock) ▸ adverb:  according to the clock ("It's three o'clock in Tokyo now") Opposite: anticlockwise, counterclockwise Phrases: ten oclock, four oclock, nine oclock, eight oclock, six oclock, more... ▸ Words similar to o'clock ▸ Usage examples for o'clock ▸ Idioms related to o'clock ▸ Wikipedia articles (New!) ▸ Words that often appear near o'clock ▸ Rhymes of o'clock ▸ Invented words related to o'clock