The width-to-height proportion of a film or television image.
The span-to-mean-chord proportion of an airfoil.
The proportion of an object's longest measurement to its next-longest dimension.
The proportion of circumference to height in an appartment surface or 2-dimensional abstract construction, such as for instance a picture, personality, or pixel. 4:3 (or 1.33:1) could be the standard proportion for NTSC movie. 1.85:1 and 2.35:1 are the typical aspect ratios for motion pictures.