We found 19 dictionaries that define the word f region:

General (13 matching dictionaries)

1. F region: Merriam-Webster
2. F region: American Heritage Dictionary of the English Language
3. F region: Collins English Dictionary
4. F region: Vocabulary.com
5. F region: Infoplease Dictionary
6. F region: Dictionary.com
7. F region: Wikipedia, the Free Encyclopedia
8. F region: Rhymezone
9. f region: FreeDictionary.org
10. f region: Mnemonic Dictionary
11. F region: TheFreeDictionary.com
12. F region: Merriam-Webster
13. F region: Wiktionary

Computing (1 matching dictionary)

14. F region: Encyclopedia

Science (1 matching dictionary)

15. F Region: Extragalactic Astronomy

Slang (1 matching dictionary)

16. F region: Urban Dictionary

Tech (3 matching dictionaries)

17. Glossary of Meteorology (No longer online)
18. National Weather Service Glossary (No longer online)
19. SOLAR-TERRESTRIAL TERMS (No longer online)

(Note: See f_regions as well.)

Definitions from Wiktionary (F region) ▸ noun:  The middle layer of the ionosphere, located 90 km (56 mi) to 150 km (93 mi) above the surface of the Earth. Opposite: lower atmosphere, D region, E region, ionosphere ▸ Words similar to f region ▸ Usage examples for f region ▸ Idioms related to f region ▸ Wikipedia articles (New!) ▸ Words that often appear near f region ▸ Rhymes of f region ▸ Invented words related to f region