An assistant to a chef or cook; a kitchen servant, a scullion. Also in extended use, as a term of abuse: a man of low birth or status; a knave, a rogue, a scoundrel. Now archaic (Scottish in later use).
Late Middle English; earliest use found in Kyng Alisaunder. From Anglo-Norman cuistron, cuistroun, quistron, quistroun, Middle French coestron, coisteron, coistron, questron assistant to a cook, scullion, knave, rogue, scoundrel, person born out of wedlock.