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Noun edit

5.1 (uncountable)

  1. (attributive) A six-channel surround sound audio system, having five full-bandwidth channels and one low-frequency effects channel.
    • 2006, Ben Hardwidge, Building Extreme PCs: The Complete Guide to Computer Modding:
      Unless you have the space to set up a mini IMAX in your living room, your best bet is to get a decent 2.1 or 5.1 speaker set.