1.nounThe ratio of an object's longest dimension to its next-longest dimension.
2.nounThe ratio of width to height in a flat surface or 2-dimensional abstract construction, such as an image, character, or pixel. 4:3 (or 1.33:1) is the standard ratio for NTSC video. 1.85:1 and 2.35:1 are the most common aspect ratios for motion pictures.