High Quality Content by WIKIPEDIA articles! In typography, the x-height or corpus size refers to the distance between the baseline and the mean line in a typeface. TYpically, this is the height of the letter x in the font (the source of the term), as well as the u, v, w, and z. (Curved letters such as a, c, e, m, n, o, r and s tend to exceed the x-height slightly, due to overshoot.) However, in modern typography, the x-height is simply a design characteristic of the font, and while an x is usually exactly one x-height in height, in some more decorative or script designs, this may not always be the case.