What is another word for "respondent"?

Roget's Thesaurus (1911) lists these synonyms for "respondent": acknowledge, acknowledgment, answer, antiphon, antiphony, because, cause, clue, conclusive, counter, determine, discover, discovery, echo, eureka, explain, explanation, fathom, for, give, hunt, indication, inquire, interpret, oracle, out, password, rationale, rebut, rebutter, record, rejoin, rejoinder, repartee, replication, reply, rescript, rescription, respond, response.