master copy

Short definition from Wiktionary

Noun

1. 1
   The copy that acts as the main or original version among several copies, such as the master proof where changes from other author copies are combined, or a similar master manuscript with edits transferred to it.
2. 2
   An original copy of a document, digital file, stencil, or other item that acts as the main version used to create all other copies, such as photocopies, printouts, or duplicates made by various methods.
3. 3
   A copy of a famous artwork made for purposes such as practice, enjoyment, respect, or imitation.

Verb

1. 1
   To transfer edits to a master copy from various stakeholders' copies (as for example with multiple authors and editors).
2. 2
   To make a copy of a masterpiece.