random-access memory

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RAM.

The part of a computer’s memory available to execute programs and temporarily store data. The memory to which the operator has random access can usually be used for both reading and writing. Unless the file has been saved, RAM data are automatically erased when the computer is turned off.

The noun has one meaning:

Meaning #1: the most common computer memory which can be used by programs to perform necessary tasks while the computer is on; an integrated circuit memory chip allows information to be stored or accessed in any order and all storage locations are equally accessible
  Synonyms: random access memory, random memory, RAM, read/write memory