From stake + holder.
Wikipedia stakeholder (plural stakeholders)
- A person holding the stakes of bettors, with the responsibility of delivering the pot to the winner of the bet.
- An escrow agent or custodian.
- (law) A person filing an interpleader action, such as a garnishee or trustee, who acknowledges possession of property that is owed to one or more of several other claimants.
- A person or organisation with a legitimate interest in a given situation, action or enterprise.
Usage notes 
The last definition essentially contradicts the historic definitions and hence the word has become a contronym. The last definition refers to one who has an interest in an issue, whereas the initial definitions refer to one who does not have an interest in the property held. The last definition has gained significant use since the 1990s, especially when discussing corporate governance.
person or organisation with a legitimate interest