We found 30 dictionaries that define the word mainsail:

General (23 matching dictionaries)

1. mainsail: Longman Dictionary of Contemporary English
2. mainsail: Merriam-Webster
3. mainsail: Oxford Learner's Dictionaries
4. mainsail: American Heritage Dictionary of the English Language
5. mainsail: Collins English Dictionary
6. mainsail: Vocabulary.com
7. Mainsail, mainsail: Wordnik
8. mainsail: Wiktionary
9. mainsail: Webster's New World College Dictionary, 4th Ed.
10. mainsail: The Wordsmyth English Dictionary-Thesaurus
11. mainsail: Infoplease Dictionary
12. Mainsail, mainsail: Dictionary.com
13. Mainsail: Wikipedia, the Free Encyclopedia
14. Mainsail: Online Plain Text English Dictionary
15. mainsail: Webster's Revised Unabridged, 1913 Edition
16. mainsail: Rhymezone
17. Mainsail: AllWords.com Multi-Lingual Dictionary
18. mainsail: FreeDictionary.org
19. mainsail: The Phrontistery - A Dictionary of Obscure Words
20. mainsail: Mnemonic Dictionary
21. mainsail: TheFreeDictionary.com

Computing (2 matching dictionaries)

22. MAINSAIL: Free On-line Dictionary of Computing
23. mainsail: Encyclopedia

Medicine (1 matching dictionary)

24. online medical dictionary (No longer online)

Miscellaneous (1 matching dictionary)

25. MAINSAIL: Acronym Finder

Sports (1 matching dictionary)

26. Mainsail: Sports Definitions

Tech (2 matching dictionaries)

27. SeaTalk Dictionary of English Nautical Language (No longer online)
28. Mainsail, Mainsail: Latitude Mexico

(Note: See mainsails as well.)

Definitions from Wiktionary ( ) ▸ noun:  (nautical) The largest (or only) sail on a sailing vessel. Similar: mainmast, topmast, royal mast, royal, flagship, supermaxi, big gun, launch, top-flag, main, more... Opposite: jib, foresail, headsail Adjectives: reefed, big, large, new, great, aft, huge, whole, full, headed, footed ▸ Words similar to mainsail ▸ Usage examples for mainsail ▸ Idioms related to mainsail ▸ Wikipedia articles (New!) ▸ Popular adjectives describing mainsail ▸ Words that often appear near mainsail ▸ Rhymes of mainsail ▸ Invented words related to mainsail