Definitions
1.nounAn indefeasible right or title, distinguished from a contingent interest, which could be defeated (i.e. cease) if a certain event occurred.
2.nounA fixed right granted to an employee, especially under a pension plan
3.nounA stake, often financial, in a particular outcome
4.nounA group of people or organizations with such a stake
5.nounAn exceptionally strong interest in protecting or promoting something to one's own advantage