We found 9 dictionaries that define the word ethnic groups:

General (3 matching dictionaries)

1. ethnic groups: Vocabulary.com
2. ethnic groups: Wiktionary
3. Ethnic groups: Wikipedia, the Free Encyclopedia

Business (1 matching dictionary)

4. Ethnic groups: Legal dictionary

Computing (1 matching dictionary)

5. Ethnic groups: Encyclopedia

Medicine (3 matching dictionaries)

6. Medical Dictionary (No longer online)
7. online medical dictionary (No longer online)
8. Ethnic groups: Medical dictionary

Miscellaneous (1 matching dictionary)

9. Sociology (No longer online)

(Note: See ethnic_group as well.)

Definitions from Wiktionary (ethnic group) ▸ noun:  A group of people who identify with one another, especially on the basis of ancestral, national, linguistic, cultural, historical or religious grounds. ▸ Also see ethnic_group Phrases: Ethnic groups in Europe, Ethnic groups in Russia, Ethnic groups in South Africa, South Asian ethnic groups, Ethnic groups in Asia, more... ▸ Words similar to ethnic groups ▸ Usage examples for ethnic groups ▸ Idioms related to ethnic groups ▸ Wikipedia articles (New!) ▸ Words that often appear near ethnic groups ▸ Rhymes of ethnic groups ▸ Invented words related to ethnic groups