noun
negotiator
nih-GOH-shee-ay-ter/nɪˈɡəʊʃieɪtər/
A person who conducts discussions to reach an agreement.
The negotiator listens carefully as the two representatives discuss their terms.

Etymology
Doing business expanded in meaning to include bargaining over terms. A negotiator, originally a businessperson, became someone who conducts those discussions to reach an agreement.
In context
the EU negotiator told the committee in September that negotiations must be finished by November this year to allow a time for the legal text of the withdrawal agreement to be finalized
More examples
- Union negotiators ask for higher wages and safer working conditions.
- She is a skilled negotiator who gets fair prices from suppliers.
- Both countries send negotiators to work out a peace agreement.
Forms
negotiator · negotiators
negotiate verb — Discuss terms to reach an agreement.
negotiation noun — Discussion aimed at reaching an agreement.