wart

n. A small, crock y 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 for obtaining ASCII characters in a foreign environment
is a wart. See also miswart.