respondent

Concise Oxford English Dictionary © 2008 Oxford University Press:
respondent/rɪˈspɒndənt/

▶noun

• 1 Law a party against whom a petition is filed, especially one in an appeal or a divorce case.

• 2 a person who responds to a questionnaire or an advertisement.

▶adjective

• 1 Law in the position of a party defending against a petition.

• 2 responding to something.

• 3 Psychology involving or denoting a response to a specific stimulus.