proxy

Used as a proxy or acting as a proxy.

a proxy indicator

a proxy measurement

An agent or substitute authorized to act for another person.

Every peer […] may make another lord of parliament his proxy, to vote for him in his absence.

The authority to act for another, especially when written.

I have no man's proxy: I speak only for myself.

The written appointment of a proctor in suits in the ecclesiastical courts

A measurement of one physical quantity that is used as an indicator of the value of another

An interface for a service, especially for one that is remote, resource-intensive, or otherwise difficult to use directly.

To serve as a proxy for.

In many of the studies we reviewed, it is common practice to use an observed variable to proxy for a relevant variable that could not be observed.

To function as a server for a client device, but pass on the requests to another server for service.