We found 24 dictionaries that define the word interest group:

General (17 matching dictionaries)

1. interest group: Merriam-Webster
2. interest group: American Heritage Dictionary of the English Language
3. interest group: Collins English Dictionary
4. interest group: Vocabulary.com
5. interest-group: Wordnik
6. interest group: Cambridge Advanced Learner's Dictionary
7. interest group: Wiktionary
8. interest group: Infoplease Dictionary
9. interest-group, interest group: Dictionary.com
10. Interest group (disambiguation), Interest group: Wikipedia, the Free Encyclopedia
11. interest group: Rhymezone
12. interest group: FreeDictionary.org
13. interest group: Mnemonic Dictionary
14. interest-group, interest group: TheFreeDictionary.com
15. interest group: Longman Dictionary of Contemporary English

Business (3 matching dictionaries)

16. Nelson Political Science Glossary (No longer online)
17. interest-group, interest group: Legal dictionary
18. BusinessDictionary.com (No longer online)

Computing (1 matching dictionary)

19. interest-group, interest group: Encyclopedia

Medicine (1 matching dictionary)

20. online medical dictionary (No longer online)

Miscellaneous (2 matching dictionaries)

21. Sociology (No longer online)
22. Political (No longer online)

(Note: See interest_groups as well.)

Definitions from Wiktionary (interest group) ▸ noun:  An advocacy group. Similar: interest, special interest group, lobby group, campaign group, pressure group, collective, side, hate group, counteradvocacy, ideologue, more... Opposite: uninterested group, disinterested group, apathetic group Phrases: special interest group, Bluetooth Special Interest Group, Public Interest Research Group, of interest to a group of people, more... ▸ Words similar to interest group ▸ Usage examples for interest group ▸ Idioms related to interest group ▸ Wikipedia articles (New!) ▸ Words that often appear near interest group ▸ Rhymes of interest group ▸ Invented words related to interest group