If you gauge the speed or strength of something, or if you gauge an amount, you measure or calculate it, often by using a device of some kind.

A gauge is a device that measures the amount or quantity of something and shows the amount measured.

If you gauge people's actions, feelings, or intentions in a particular situation, you carefully consider and judge them.

A gauge of someone's feelings or a situation is a fact or event that can be used to judge them.

A gauge is the distance between the two rails on a railway line.

A gauge is the thickness of something, especially metal or wire.