We found 40 dictionaries that define the word billion:

General (27 matching dictionaries)

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

Art (1 matching dictionary)

26. Billion: Numismatic Dictionary

Business (1 matching dictionary)

27. BusinessDictionary.com (No longer online)

Computing (2 matching dictionaries)

28. billion: CCI Computer
29. Billion (disambiguation), billion: Encyclopedia

Miscellaneous (1 matching dictionary)

30. billion: Wordcraft Dictionary

Science (5 matching dictionaries)

31. Billion: Eric Weisstein's World of Mathematics
32. Billion: Extragalactic Astronomy
33. billion: Nine Planets Glossary
34. How Many? A Dictionary of Units of Measurement (No longer online)
35. BILLION: Zoom Astronomy Glossary

Slang (1 matching dictionary)

36. Billion: Urban Dictionary

Tech (2 matching dictionaries)

37. Basics of Space Flight Glossary (No longer online)
38. Lake and Water Word Glossary (No longer online)

(Note: See billions as well.)

Definitions from Wikipedia ( ) ▸ noun:  a name for a large number. Opposite: few, little, minor, small, scant Types: million, trillion, quadrillion, quintillion, sextillion, septillion, octillion, nonillion, more... Phrases: a billion, one billion, multi billion, billion dollar grass, Parts per Billion, more... Adjectives: multi, half, two, per, top, ten, 100, worth, fifty, 150, six Colors:     gold,     silver,     platinum,     emerald,     sapphire, more... ▸ Word origin ▸ Words similar to billion ▸ Usage examples for billion ▸ Idioms related to billion ▸ Wikipedia articles (New!) ▸ Popular adjectives describing billion ▸ Words that often appear near billion ▸ Rhymes of billion ▸ Invented words related to billion