We found 34 dictionaries that define the word thinner:

General (25 matching dictionaries)

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

Business (2 matching dictionaries)

24. Construction Term Glossary (No longer online)
25. thinner: Legal dictionary

Computing (1 matching dictionary)

26. thinner: Encyclopedia

Medicine (1 matching dictionary)

27. thinner: Medical dictionary

Miscellaneous (1 matching dictionary)

28. thinner: Idioms

Slang (1 matching dictionary)

29. thinner: Urban Dictionary

Tech (3 matching dictionaries)

30. Book Binding (No longer online)
31. AUTOMOTIVE TERMS (No longer online)
32. Schlumberger Oilfield Glossary (No longer online)

(Note: See thin as well.)

Definitions from Wiktionary ( ) ▸ noun:  A liquid substance used to thin the consistency of another liquid. ▸ noun:  Something that thins or thins out (another thing). Similar: dilutant, solvent, resolvent, dissolvent, dissolving agent, diluter, paint thinner, diluent, thickening agent, dilution, more... Opposite: fatter, thicker, heavier Types: lacquer thinner, mineral spirits, naphtha, acetone, methylene chloride, more... Phrases: paint thinner, Lacquer thinner, blood thinner, get thinner, thinner than thin, more... Colors:     pale blue,     light gray,     white,     silver,     ivory, more... ▸ Word origin ▸ Words similar to thinner ▸ Usage examples for thinner ▸ Idioms related to thinner ▸ Wikipedia articles (New!) ▸ Popular adjectives describing thinner ▸ Words that often appear near thinner ▸ Rhymes of thinner ▸ Invented words related to thinner