What is the terminology used in computer security where you need at least two admins at the same time to login/access a database/resources? Maybe by each having part of the password or key. This used in access-control sometimes too.
It is called the Two-man rule.
In Saltzer and Schroeder's Security Principles, this is called "Separation of Privilege".
"e) Separation of privilege: Where feasible, a protection mechanism that requires two keys to unlock it is more robust and flexible than one that allows access to the presenter of only a single key. The relevance of this observation to computer systems was pointed out by R. Needham in 1973. The reason is that, once the mechanism is locked, the two keys can be physically separated and distinct programs, organizations, or individuals made responsible for them. From then on, no single accident, deception, or breach of trust is sufficient to compromise the protected information. This principle is often used in bank safe-deposit boxes. It is also at work in the defense system that fires a nuclear weapon only if two different people both give the correct command. In a computer system, separated keys apply to any situation in which two or more conditions must be met before access should be permitted. For example, systems providing user-extendible protected data types usually depend on separation of privilege for their implementation."
Depends of the norm/standard but most of the time it's called dual control or split knowledge.