noun

1. 1. a casing of strong fabric filled with cotton, hair, foam rubber, etc., usually containing coiled springs, often quilted or tufted at intervals, and used on or as a bed
   2. an inflatable pad used in the same way
      in full air mattress
2. a mass or mat of interwoven brushwood, poles, etc. used to protect an embankment or dike from erosion, etc.

Etymology: ME materas < OFr < It materasso < Ar maṭraḥ, place where something is thrown or laid, cushion