gatefold
ˈɡeɪtˌfəʊld
Definitions
1. noun
A type of album cover that folds out to reveal additional content, typically artwork or lyrics.
“The new album’s gatefold features a stunning illustration of the band’s history.”
2. verb
To fold an album cover out to reveal additional content.
“If you gatefold the album correctly, the hidden artwork will be revealed.”