n (computing) A portion of memory set aside to store data, often before it is sent to an external device or as it is received from an external device.
n (mechanical) Anything used to maintain slack or isolate different objects.
n (telecommunications) A routine or storage medium used to compensate for a difference in rate of flow of data, or time of occurrence of events, when transferring data from one device to another.
n (rail) A device on trains and carriages designed to cushion the impact between them.
n (rail) The metal barrier to help prevent trains from running off the end of the track.