Copyholder and Mechanical device

Copyholder noun - Mechanical device used in printing; holds the copy for the compositor.

Mechanical device and copyholder are semantically related. In some cases you can use "Mechanical device" instead a noun "Copyholder".

Mechanical device noun - Mechanism consisting of a device that works on mechanical principles.

Copyholder and mechanical device are semantically related. Sometimes you can replace term "Copyholder" with "Mechanical device", this terms are similar.