mattressn.[OF. materas, F. matelas, LL. matratium; cf. Sp. & Pg. almadraque, Pr. almatrac; all from Ar. marah a place where anything is thrown, what is thrown under something, fr. araha to throw.]()1. A large pad stuffed with hair, moss, or other suitable soft material, and quilted or otherwise fastened, used as or in a bed, to support the human body while lying down.()2. (Hydraulic Engin.) A mass of interwoven brush, poles, etc., to protect a bank from being worn away by currents or waves.()innerspring mattress A variety of mattress{1} having springs inside to provide a flexible support; it is considered more comfortable than a stuffed mattress.()