We found 22 dictionaries that define the word f number:

General (16 matching dictionaries)

1. f-number: Merriam-Webster
2. f-number: Oxford Learner's Dictionaries
3. f-number: American Heritage Dictionary of the English Language
4. f-number, f-number, f number: Collins English Dictionary
5. f number: Vocabulary.com
6. F-number, f-number: Wordnik
7. f-number: Wiktionary
8. f-number: Webster's New World College Dictionary, 4th Ed.
9. f-number: The Wordsmyth English Dictionary-Thesaurus
10. f-number: Infoplease Dictionary
11. f-number, f number: Dictionary.com
12. F-Number, F-number, F-number (disambiguation), F number: Wikipedia, the Free Encyclopedia
13. f number: Rhymezone
14. f number: FreeDictionary.org
15. f number: Mnemonic Dictionary
16. f-number, f number: TheFreeDictionary.com

Computing (1 matching dictionary)

17. f-number, f number: Encyclopedia

Medicine (1 matching dictionary)

18. f-number, f number: Medical dictionary

Science (2 matching dictionaries)

19. f Number: Extragalactic Astronomy
20. How Many? A Dictionary of Units of Measurement (No longer online)

Tech (2 matching dictionaries)

21. f-Number: Nikonians Photo Glossary
22. Glossary of Film/Video Terms (No longer online)

(Note: See f_numbers as well.)

Definitions from Wikipedia (F number) ▸ noun:  a correlation number used in the analysis of polycyclic aromatic hydrocarbons (PAHs) as a descriptor of their hydrophobicity and molecular size. ▸ Words similar to f number ▸ Usage examples for f number ▸ Idioms related to f number ▸ Wikipedia articles (New!) ▸ Words that often appear near f number ▸ Rhymes of f number ▸ Invented words related to f number