What is Amanuensis?

Legal Definition
An amanuensis (/əˌmænjuːˈɛnsɪs/) is a person employed to write or type what another dictates or to copy what has been written by another, and also refers to a person who signs a document on behalf of another under the latter's authority.
-- Wikipedia
Legal Definition
Oe who write another dictates. About the beginning of the sixth century,, the tabellions (q.v.) were known by this name. 1 Sav. Dr. Rom. Moy. Age, n. 16.
-- Bouviers Law Dictionary
Legal Definition
One who writes on behalf of another that which he dictates.
-- Black's Law Dictionary