the.com/gypsum board

means A building panel made of a gypsum plaster core sandwiched between two sheets of paper, used to form the interior walls and ceilings of most modern buildings — better known as drywall or plasterboard.

from The core material, gypsum, gets its name from the Greek 'gypsos' (plaster/chalk), via Latin 'gypsum' — a mineral humans have calcined and smeared on walls since antiquity. The modern boxed-up version, sandwiching set gypsum plaster between paper liners, was developed in the late 19th century as a faster, fire-resistant alternative to wet lath-and-plaster walls, and trademarked names like Sheetrock later became near-generic for the product.