We found 21 dictionaries that define the word responder:

General (15 matching dictionaries)

1. responder: Merriam-Webster
2. responder: Oxford Learner's Dictionaries
3. responder: Collins English Dictionary
4. responder: Vocabulary.com
5. Responder, responder: Wordnik
6. responder: Wiktionary
7. responder: Webster's New World College Dictionary, 4th Ed.
8. responder: The Wordsmyth English Dictionary-Thesaurus
9. responder: Infoplease Dictionary
10. responder: Dictionary.com
11. Responder: Wikipedia, the Free Encyclopedia
12. responder: Rhymezone
13. responder: FreeDictionary.org
14. responder: Mnemonic Dictionary
15. responder: TheFreeDictionary.com

Business (1 matching dictionary)

16. responder: Legal dictionary

Computing (1 matching dictionary)

17. responder: Encyclopedia

Medicine (2 matching dictionaries)

18. responder: Merriam-Webster Medical Dictionary
19. responder: Medical dictionary

Tech (2 matching dictionaries)

20. Glossary of Meteorology (No longer online)
21. SeaTalk Dictionary of English Nautical Language (No longer online)

(Note: See respond as well.)

Definitions from Wiktionary (responder) ▸ noun:  One who responds. ▸ noun:  A person who responds to an emergency situation or other summons. Similar: respondent, answerer, responser, respondee, seroresponder, counterrespondent, replier, underresponder, responsal, replicant, more... Opposite: initiator, instigator, provocateur Phrases: first responder, auto responder, The Responder, First Responder Network Authority, Emergency medical responder levels by U.S. state, more... Adjectives: first, non, low, high, passive, poor, partial, complete, next, initial, primary Colors:     red,     blue,     white,     yellow,     orange, more... ▸ Words similar to responder ▸ Usage examples for responder ▸ Idioms related to responder ▸ Wikipedia articles (New!) ▸ Popular adjectives describing responder ▸ Words that often appear near responder ▸ Rhymes of responder ▸ Invented words related to responder