The Collaborative International Dictionary of English v.0.48:

DAT \DAT\ n. [acronym, from Digital AudioTape.]
   digital audiotape, a digitally encoded tape recording of
   sound; -- in contrast to the usual analog audio tape.
   [acronym]
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

DAT
    n 1: a digital tape recording of sound [syn: digital
         audiotape, DAT]

The Free On-line Dictionary of Computing (19 January 2023):

DAT

   1. Digital Audio Tape.

   2. Dynamic Address Translation.