1. a person who responds or replies to something
2. a person who reacts to an emergency situation, especially a trained professional
3. a person who participates in a survey, study, or research by providing answers
Usage: research context

Examples

• The survey had over 500 responders from different age groups.
• First responders arrived at the accident scene within minutes.
• She was the only responder to the job posting that day.
• Emergency responders worked through the night to help victims.
• The researcher analyzed data from all survey responders.
• Police and fire responders coordinated their rescue efforts.
• Each responder in the study received a small payment for participation.