(1) A means of preventing uncommitted changes made by one application process from being perceived by another application process and for preventing one application process from updating data that is being accessed by another process. A lock ensures the integrity of data by preventing concurrent users from accessing inconsistent data.
(2) The process by which integrity of data is ensured by preventing more than one user from accessing or changing the same data or object at the same time.
(3) A mechanism with which a resource is restricted for use by the holder of the lock.
(4) A means of serializing a sequence of events or serializing access to data.
(5) To temporarily restrict resources to provide protection from concurrent users of the system.