WordNet (r) 3.0 (2006):

read-only memory
    n 1: (computer science) memory whose contents can be accessed
         and read but cannot be changed [syn: read-only memory,
         ROM, read-only storage, fixed storage]

The Free On-line Dictionary of Computing (30 December 2018):

Read-Only Memory
ROM

    (ROM) A type of data storage device which is
   manufactured with fixed contents.  In its most general sense,
   the term might be used for any storage system whose contents
   cannot be altered, such as a gramophone record or a printed
   book; however, the term is most often applied to
   semiconductor integrated circuit memories, of which there
   are several types, and CD-ROM.

   ROM is inherently non-volatile storage - it retains its
   contents even when the power is switched off, in contrast to
   RAM.

   ROM is often used to hold programs for embedded systems
   since these usually have a fixed purpose.  ROM is also used
   for storage of the lowest level bootstrap software
   (firmware) in a computer.

   See also Programmable Read-Only Memory.

   (1995-05-09)