proxy

noun
1
the authority that you give to somebody to do something for you, when you cannot do it yourself
وکالت, نمایندگی, اختیار
2
a person who has been given the authority to represent somebody else
نماینده, وکیل
Your proxy will need to sign the form on your behalf.
They were like proxy parents to me.
She is acting as proxy for her husband.
3
something that you use to represent something else that you are trying to measure or calculate
نماینده, واسطه, شاخص, نمایانگر, معرف
The number of patients on a doctor's list was seen as a good proxy for assessing how hard they work.