1. a person hired to kill someone, as a gunfighter or professional killer.
2. a person hired to bear arms and fight for another, as a bodyguard or mercenary.
3. a person, as a politician or lobbyist, skilled at attaining power for others.
4. a person hired to resolve difficult problems or disputes or to handle complex legal or business problems.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.