We found 6 dictionaries that define the word onis:

General (4 matching dictionaries)

1. ONIS: Vocabulary.com
2. Oni's, Onis, onis: Wordnik
3. onis: Wiktionary
4. Onis: Wikipedia, the Free Encyclopedia

Miscellaneous (1 matching dictionary)

5. ONIS: Acronym Finder

Slang (1 matching dictionary)

6. Onis: Urban Dictionary

(Note: See oni as well.)

Definitions from Wiktionary (ONI) ▸ noun:  A Japanese evil spirit or demon. ▸ noun:  (US military) Initialism of Office of Naval Intelligence. ▸ Also see oni ▸ Words similar to onis ▸ Usage examples for onis ▸ Idioms related to onis ▸ Wikipedia articles (New!) ▸ Popular adjectives describing onis ▸ Words that often appear near onis ▸ Rhymes of onis ▸ Invented words related to onis