vellum
OAB Definition
writing support made of untanned calf skin which has been stretched, thinned, and dried.
The term is sometimes used interchangeably with “parchment,” which can be made of any animal skin. Determining the difference between materials is not always possible without testing, so parchment is the more commonly used term.
In contemporary use, vellum or parchment refers to a commercially formed sheet of cellulose fibers that offers similar qualities to the prepared animal skin. The sheets are translucent, stiff, and plastic-like. Parchment has a cloudier look than vellum.