We found 20 dictionaries that define the word M-1:

General (16 matching dictionaries)

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

Business (1 matching dictionary)

17. M-1: Financial dictionary

Computing (1 matching dictionary)

18. M-1: Encyclopedia

Miscellaneous (1 matching dictionary)

19. M-1: Acronym Finder

Slang (1 matching dictionary)

20. M-1: Urban Dictionary

(Note: See m-1s as well.)

Definitions from WordNet (M-1) ▸ noun:  a semiautomatic rifle Similar: Garand, garand rifle, m-1 rifle, d-1, Quaker gun, big gun, hired gun, shoot-'em-up, shotgun wedding, warning shot, more... Opposite: m+1, positive m, greater thm Phrases: m-1 rifle, m-2 and m-3 m-1, M-1 Global, M-1 Grand Prix, Aerojet M-1, more... ▸ Words similar to M-1 ▸ Usage examples for M-1 ▸ Idioms related to M-1 ▸ Wikipedia articles (New!) ▸ Popular adjectives describing M-1 ▸ Words that often appear near M-1 ▸ Rhymes of M-1 ▸ Invented words related to M-1