Definition of mattress
1 a
: a fabric case filled with resilient material (such as cotton, hair, feathers, foam rubber, or an arrangement of coiled springs) used either alone as a bed or on a bedstead
b
: an inflatable airtight sack for use as a mattress
2
: a device (as of interwoven brush and poles) used to protect a shoreline, bank, or streambed from erosion
