We found 23 dictionaries that define the word o ring:

General (15 matching dictionaries)

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

Business (1 matching dictionary)

16. Construction Term Glossary (No longer online)

Computing (1 matching dictionary)

17. O-ring, O ring: Encyclopedia

Medicine (1 matching dictionary)

18. O-ring, O ring: Medical dictionary

Slang (1 matching dictionary)

19. THE O-RING, o- ring, o-ring, o ring: Urban Dictionary

Sports (1 matching dictionary)

20. O-ring: Sports Definitions

Tech (3 matching dictionaries)

21. AUTOMOTIVE TERMS (No longer online)
22. Schlumberger Oilfield Glossary (No longer online)
23. Oil and Gas Well Drilling and Servicing eTool (No longer online)

(Note: See o_ringing as well.)

Definitions from WordNet (O ring) ▸ noun:  a gasket consisting of a flat ring of rubber or plastic; used to seal a joint against high pressure ▸ Words similar to o ring ▸ Usage examples for o ring ▸ Idioms related to o ring ▸ Wikipedia articles (New!) ▸ Words that often appear near o ring ▸ Rhymes of o ring ▸ Invented words related to o ring