a large pad for supporting the reclining body, used as or on a bed, consisting of a quilted or similarly fastened case, usually of heavy cloth, that contains hair, straw, cotton, foam rubber, etc., or a framework of metal springs.
late 13c., from O.Fr. materas, from It. materasso, from M.L. matracium, borrowed in Sicily from Arabic al-matrah "the cushion" (cf. Sp. almadraque "mattress"), lit. "the thing thrown down," from taraha "he threw (down)."