One who takes part in dialogue or conversation; a talker, interpreter, or questioner.
Adopted by Greg Egan as a name for AI software that acts as an answering service.
The screen icon for my interlocutor was a three-holed torus tiled with triangles, endlessly turning itself inside out.
Definition from the GNU version of the Collaborative International Dictionary of English (via Wordnik)
metonymic / autodidactic 