/glas T-T-Y/ or /glas ti'tee/ A terminal that has a display screen but which, because of hardware or software limitations, behaves like a teletype or some other printing terminal, thereby combining the disadvantages of both: like a printing terminal, it can't do fancy display hacks, and like a display terminal, it doesn't produce hard copy. An example is the early "dumb" version of Lear-Siegler ADM 3 (without cursor control). See tube, tty; compare dumb terminal, smart terminal. See "TV Typewriters" for an interesting true story about a glass tty.