We found 10 dictionaries that define the word user ID:

General (5 matching dictionaries)

1. user ID: Merriam-Webster
2. user id, user ID: Cambridge Advanced Learner's Dictionary
3. user ID: Dictionary.com
4. User ID: Wikipedia, the Free Encyclopedia
5. user ID: Wiktionary

Business (1 matching dictionary)

6. BusinessDictionary.com (No longer online)

Computing (2 matching dictionaries)

7. user id: Free On-line Dictionary of Computing
8. user ID: Encyclopedia

Medicine (1 matching dictionary)

9. online medical dictionary (No longer online)

Miscellaneous (1 matching dictionary)

10. USER ID: Acronym Finder

Definitions from Wiktionary (user ID) ▸ noun:  Synonym of username ▸ Words similar to user ID ▸ Usage examples for user ID ▸ Idioms related to user ID ▸ Wikipedia articles (New!) ▸ Words that often appear near user ID ▸ Rhymes of user ID ▸ Invented words related to user ID