responder
US
UK responder n: (electronics)
SC 响应器 xiǎng yìng qì
TC 響應器
TC 響應器
SC 应答器 xiǎng yìng qì，yìng dá qì
The word transponder is a combination of transmitter and responder.
responder n: (person who answers)
SC 回答者 huí dá zhě
SC 回应者 huí dá zhě，huí yìng zhě
The responder answered the question by saying, "I don't know."
first responder n: (emergency medic)
SC 现场应急人员
The first responders saved many lives after the bombing.