mattress

plural mattresses

1. A pad on which a person can recline and sleep, usually having an inner section of coiled springs covered with foam or other cushioning material then enclosed with cloth fabric.
2. A form of retaining wall used to support foundations or an embankment
3. A form of lagging, in particular for boilers.

   The boiler and firebox are lagged with a lightweight Fibreglass mattress.

   1951 March, “British Railways Standard "Britannia" Class 4-6-2 Locomotives”, in Railway Magazine, page 185

   1 more example

   Spun glass mattresses are used for lagging the boiler, which has three Ross pop safety valves on the front ring.

   1941 April, “British Locomotive Developments”, in The Railway Magazine, London: Tothill Press, →ISSN, →OCLC, page 173

present singular third person mattresses · participle present mattressing · participle past mattressed · past mattressed

1. transitiveTo cover with a thick layer, like a mattress; to blanket.

   A comfortable litter of pine needles had mattressed the ground and spreading branches had been a canopy overhead.

   1997, Andrew R. M. Patterson, A planet through a field of stars, page 123