Source : Webster's Revised Unabridged Dictionary (1913)

Negotiator \Ne*go"ti*a`tor\, n. [L.: cf. F. n['e]gociateur.]
   One who negotiates; a person who treats with others, either
   as principal or agent, in respect to purchase and sale, or
   public compacts.

Source : WordNet®

negotiator
     n : someone who negotiates (confers with others in order to
         reach a settlement) [syn: {negotiant}, {treater}]