Duchsustus (Hebrew: דוכסוסטוס, from Greek δυσχιστός dyschistos) is the name of a type of parchment used for religious writings in Judaism.
[1] It is originally a Greek word and one of three Talmudic names for animal skin.
The meanings of these terms, however, are the subject of controversy in Jewish law.
[4] Duchsustus is the animal's dermis, klaf is the epidermis, and gevil is both layers tanned and unseparated.
[5] According to Maimonides, Torah scrolls must be written on g'vil only on the side on which the hair had grown, and never on duchsustos (understood as the half-skin from the flesh side).