We found 20 dictionaries that define the word onomastics:

General (16 matching dictionaries)

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

Medicine (1 matching dictionary)

17. onomastics: Medical dictionary

Miscellaneous (2 matching dictionaries)

18. onomastics: A Word A Day
19. onomastics: Wordcraft Dictionary

Tech (1 matching dictionary)

20. Rane Professional Audio Reference (No longer online)

(Note: See onomastic as well.)

Definitions from Wiktionary (onomastics) ▸ noun:  The branch of lexicology devoted to the study of names and naming, especially the origins of names. Similar: onomatology, onomasiology, toponymy, onomast, patronomatology, odonymy, anthroponymy, toponymics, toponomastics, toponomy, more... Phrases: Celtic onomastics, more... Adjectives: literary, finnish, local, greek, personal, traditional, ancient, sacred, english, semitic, early ▸ Words similar to onomastics ▸ Usage examples for onomastics ▸ Idioms related to onomastics ▸ Wikipedia articles (New!) ▸ Popular adjectives describing onomastics ▸ Words that often appear near onomastics ▸ Rhymes of onomastics ▸ Invented words related to onomastics