write-once read-many

from The Free On-line Dictionary of Computing (8 July 2008)

Write-Once Read-Many
WORM

   <storage> (WORM) Any type of storage medium to which data can
   be written to only a single time, but can be read from any
   number of times.  Typically this is an {optical disk} whose
   surface is permanently etched using a laser in order to record
   information.  WORM media have a significantly longer shelf
   life than magnetic media and thus are used when data must be
   preserved for a long time.

   (1996-04-01)