Wart

n. A small, crocky feature that sticks out of an otherwise clean design. Something conspicuous for localized ugliness, especially a special-case exception to a general rule. For example, in some versions of 'csh(1)', single quotes literalize every character inside them except '!'. In ANSI C, the '??' syntax used obtaining ASCII characters in a foreign environment is a wart.

See also miswart.