X

1. Used in various speech and writing contexts (also in lowercase) in roughly its algebraic sense of `unknown within a set defined by context' (compare {N}). Thus, the abbreviation 680x0 stands for 68000, 68010, 68020, 68030, or 68040, and 80x86 stands for 80186, 80286, 80386, 80486, 80586 or 80686 (note that a Unix hacker might write these as 680[0-6]0 and 80[1-6]86 or 680?0 and 80?86 respectively; see {glob}).
2. [after the name of an earlier window system called `W'] An over-sized, over-featured, over-engineered and incredibly over-complicated window system developed at MIT and widely used on Unix systems.

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