mattress

noun

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.

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

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

verb

1. (transitive)To 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.”