Aspect ratio

[1] The ratio of length to width of rectangular air grille or duct.
[2] The relationship in a tire or wheel between the distance from the rim to the tread and the tire's width (i.e., ratio of section height to section width). Thus, in a P185/80R13 tire, 80 is the aspect ratio, showing the height is 80% of the width. A lower aspect ratio describes a shorter, wider tire.
[3] In a wing, it is the relationship of its span (horizontal length) to its chord (height). Important for induced drag and range/speed characteristics. Defined as S²/A where S is the span and A is the area. Normal figure between 6 and 9, lesser values than 6 being low aspect ratio, greater than 9 high aspect ratios.
[4] Ratio of the length of a fiber or wire to its width or diameter.
[5] (AR) Ratio of the width to the height of the reproduced picture or computer screen, e.g., 4x3, often expressed with the height as unity. 1.33:1. Wide-screen systems have aspect ratios between 1.65:1 and 2.35:1.
[6] In a Tokamak type of fusion machine, the ratio of the major to minor radii of the torus. See also ULP