retention

Capable of being retained.

The act of retaining or keeping; retention.

plural of retainment

The quality of being retainable.

Any of several structures used to restrain a vertical-faced mass of earth.

plural of retaining wall

plural of retaining valve

(rail transport, mechanical engineering) A device that retains some air pressure in a train's air brake cylinders even when the automatic brake valve is set to the fully-released position, used on steep downgrades to allow a degree of continuous braking effort to be maintained without depleting the pressure in the train's brakepipe (which would result in the loss of nearly all braking ability, causing a runaway).

plural of special retainer