What is "innerspring mattress"

Mattress \Mat"tress\, n. [OF. materas, F. matelas, LL. matratium; cf. Sp. & Pg. almadraque, Pr. almatrac; all from Ar. ma[.t]rah a place where anything is thrown, what is thrown under something, fr. [.t]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.