The Collaborative International Dictionary of English v.0.48:

Interlocutor \In`ter*loc"u*tor\ (?; 277), n. [Cf. F.
   interlocuteur.]
   [1913 Webster]
   1. One who takes part in dialogue or conversation; a talker,
      interpreter, or questioner. --Jer. Taylor.
      [1913 Webster]

   2. (Law) An interlocutory judgment or sentence.
      [1913 Webster]

WordNet (r) 3.0 (2006):

interlocutor
    n 1: the performer in the middle of a minstrel line who engages
         the others in talk [syn: interlocutor, middleman]
    2: a person who takes part in a conversation [syn:
       interlocutor, conversational partner]