Definition: a person whose employment is to write what another dictates, or to copy what has been written by another
Why I Looked It Up
A very strange passage in Cutting for Stone tells of an infant twin who is confronted with a woman’s breast for the first time:
Though I am in possession of the breast, stroking it, palpating it, I am also [my twin’s] amanuensis.
I suppose he was saying that he was somehow communicating with this twin about this strange thing he had found.