responder

Definition of Responder in English :

1. answerer, respondent, responder

someone who responds

WordNet Lexical Database for English. Princeton University. 2010.

Responder

noun

1.

a person or thing that responds

2. Electronics

a device that indicates reception of a signal; specif., transponder

v. re·spond·ed, re·spond·ing, re·sponds

v.intr.

1. To make a reply; answer: respond to an email.

2. To act in return or in answer: firefighters responding to a call. See Synonyms at answer.

3. To react to a stimulus or to a treatment, especially in a favorable way: tumors that responded to radiation.

v.tr.

To give as a reply; answer.

n.
Architecture

A pilaster or half-pier engaged to a wall and carrying one end of an arch or groin, often at the end of an arcade.