Buffer

[1] A machine used to rasp the old tread from the tire.
[2] An electronic amplifier, often with unity gain, which is designed to decouple input from output. Normally designed to haave high input impedance so that it does not load the driving stage and low output impedance such that it can provide current drive.
[3] A spring-loaded pad attached to the framework of railway rolling-stock to minimize the shock of collision; any resilient pad used for a resilient purpose. May be hydraulically controlled or dampened.
[4] A substance added to an electrolyte solution which prevents rapid changes in the concentration of a given ion. Also called buffer reagent See also jounce buffer