The ratio of width to height of the screen on a high-definition TV set (HDTV) or computer monitor. Also expressed as the ratio 1.78:1, a 16:9 screen provides a wider rectangle than the 4:3 ratio of earlier TV sets and monitors. However, 16:9 is not as wide as the screens in movie theaters (see aspect ratio for comparison). Watching movies that are maintained in their original theater format on a 16:9 monitor still results in letterbox viewing, with black bars at top and bottom. See letterbox and HDTV.