We found 26 dictionaries that define the word gills:

General (15 matching dictionaries)

1. gills: Merriam-Webster
2. gills: Oxford Learner's Dictionaries
3. gills: Collins English Dictionary
4. gills: Vocabulary.com
5. Gill's, Gills, gills: Wordnik
6. gills: Cambridge Advanced Learner's Dictionary
7. Gills, Gills, Gills: InfoVisual Visual Dictionary
8. Gills, gills: Wiktionary
9. gills: Dictionary.com
10. gills: Cambridge Essential American English Dictionary
11. Gills: Wikipedia, the Free Encyclopedia
12. Gills: Rhymezone
13. Gills: E Cobham Brewer, The Reader's Handbook
14. Gills: Dictionary of Phrase and Fable (1898)
15. gills: TheFreeDictionary.com

Business (1 matching dictionary)

16. Gills (biology), gills: Legal dictionary

Computing (1 matching dictionary)

17. Gills (biology), gills: Encyclopedia

Medicine (3 matching dictionaries)

18. gills: Merriam-Webster Medical Dictionary
19. Probert Encyclopaedia of Medicine (No longer online)
20. Gills (biology), gills: Medical dictionary

Miscellaneous (1 matching dictionary)

21. gills: Idioms

Science (1 matching dictionary)

22. gills: Mussel Glossary

Slang (3 matching dictionaries)

23. gills, gills: Green’s Dictionary of Slang
24. Gill's: A Seattle Lexicon
25. gills: Urban Dictionary

Sports (1 matching dictionary)

26. Gills: Sports Definitions

(Note: See gill as well.)

Definitions from WordNet (Gills) ▸ name:  A surname (common: 1 in 100000 families; popularity rank in the U.S.: #14061) Opposite: lungs Types: fish gills, mushroom gills, capillary, more... Phrases: External gills, green around the gills, green about the gills, to the gills, green at the gills, more... Adjectives: external, internal, anal, like, red, tracheal, white, large, blue, true, filamentous ▸ Words similar to gills ▸ Usage examples for gills ▸ Idioms related to gills ▸ Wikipedia articles (New!) ▸ Words that often appear near gills ▸ Rhymes of gills ▸ Invented words related to gills