Damper

[1] A friction device sometimes called a "shock absorber". Used for controlling and damping spring oscillations. The springs actually absorb road shocks; the dampers convert the energy imparted to the springs into thermal energy (by friction), which is dissipated to the atmosphere or the vehicle's chassis. Dampers are distinguishable by the type of friction involved, mechanical or hydraulic but most modern cars used tubular-shaped hydraulic shock absorbers. Because they affect up and down wheel motions, dampers are an important link in tuning a vehicle's ride and handling.
[2] A movable plate which permits or restricts the flow of liquids or gasses.
See also friction damper, gas damper, harmonic balancer, mass damper, monotube damper, piston damper, pulsation damper, steering damper, steering wheel damper, torsional vibration damper, torsion damper, twin-tube damper, vibration damper