responder

American  

[ri-spon-der] / rɪˈspɒn dər /

noun

1. a person or thing that responds.

2. Electronics. the part of a transponder that transmits the reply.

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Etymology

Origin of responder

First recorded in 1875–80; respond + -er ¹

Explanation

A responder is someone who answers a question or who acts quickly in response to some event. If there's only one responder to all of your teacher's questions, he'll start calling on other students to answer as well. Anyone who responds, or reacts, in some way is a responder, whether their responses are spoken, sung, or acted out physically. You're likely to find this word in the context of "first responders," a term that's used for police officers, firefighters, EMTs, or anyone else whose job puts them among the people who help in an emergency or disaster.

Example Sentences

When I was in Iraq, on patrol and during emergency responder training, I was given the option of picking my own radio call sign.

From Slate • Apr. 13, 2026

At Massapequa's St Rose of Lima Roman Catholic Church, which has a high percentage of cop and first responder parishioners, Rev Gerard Gentleman noted how the community moved quickly from shock to generosity and empathy.

From BBC • Apr. 10, 2026

Waymo, the self-driving car startup owned by Google parent Alphabet, plans to roll out fleetwide updates, expand its first responder engagement and update its emergency response protocol, it said in a statement Tuesday.

From The Wall Street Journal • Dec. 24, 2025

His grandson Mendy Amzalak told The Australian that he had rushed to the scene on the beach as a first responder.

From Barron's • Dec. 17, 2025

He’s a first responder with an artistic eye.

From "Drama High" by Michael Sokolove