IPA: /ˈkɒpiˌhoʊldə/
KK: /ˈkɑːpiˌhoʊldər/
A person or device that holds written material in place for reading or typesetting.
The copyholder ensured that the manuscript was easy to read during the proofreading process.
Copyholder is formed from 'copy' (from Old French *coper*, meaning to cut or to copy) and 'holder' (from Old English *holdan*, meaning to hold or keep). The term refers to someone who holds or possesses a copy of something, particularly in the context of land or property rights.
Think of someone who 'holds' ('holder') a 'copy' of something — that's why a copyholder is a person who possesses a copy.