interlocutor
Concise Oxford English Dictionary © 2008 Oxford University Press:
interlocutor /ˌɪntəˈlɒkjʊtə/
▶noun formal a person who takes part in a dialogue.
– derivatives
interlocution noun.
interlocution noun.
– origin C16: mod. L., from L. interlocut-, interloqui ‘interrupt (with speech)’, from inter- ‘between’ + loqui ‘speak’.
'interlocutor' also found in these Oxford entries:

