WORM means Write Once, Read Many. It is sometimes used when discussing computer storage media that can be written to once, but read from multiple times. Examples of such storage media are CD-R and DVD-R.

Paper has for centuries been a WORM storage medium avant la lettre.

WORM should not be confused with worm (not in capitals) (a self-replicating computer program, similar to a computer virus).

The eccentric Oliver Heaviside would sign correspondences "WORM" near the end of his life.