Interlocutor: a person who participates in a dialogue or takes part in a conversation; a talker, or a mediator between others.
Interlocutor comes from the Latin inter, meaning “between” and the Latin verb loquor, meaning “I speak”.
For example:
“After our difficult conversation, we thought it might be best to continue with the help of an interlocutor.”
“The Duke, acting as interlocutor, was speaking with the queen when the king entered the conversation.”
