We used to call it "the tube"
as in Cathode Ray Tube, or CRT.

But watch now, as technology continues its inexorable advance and liquid-crystal displays (LCDs) replace CRTs as I anticipate they will within ten years or so (LCDs are lighter, consume less power, etc.). Will we still call it the tube (or the boob tube if we want to be less respectful)? When it isn't a tube any more? Just look at what happened to the telephone - we still call people by "dialing." In Britain or Oz do they still "ring you up?" The silly devices don't even ring any more, they tweetle!

Science marches on, but sometimes language stands still.
but perhaps remains the more picturesque for it!