What does centerfold mean on a pattern sewing?

To make an etching the artist first coats the entire printing plate with an acid-resistant substance called a made from beeswax, asphalt, and other material. the artist then draws on the coated plate with an etching needle exposing the metal. next the plate is dipped in the plate is removed, the waxy coating removed, and the plate is cleaned, inked and printed.

Ineed someone to describe what they mean in the instructions !

One art critic referred to painters in the fauvism movement as "wild beasts". where did that title come from? what were some of the characteristics of fauvism?