(tai epsion chi) A typesetting language developed by Stanford professor Donald Knuth that is noted for its ability to describe elaborate scientific formulas. Pronounced "tek" or the guttural "tekhhh" (the X is the Greek chi, not the English X), TeX is widely used for mathematical book publishing throughout the world.

Knuth created the first prototype of TeX in 1978 to avoid having to continue using the Unix troff program to typeset his book series, "The Art of Computer Programming." It took eight years of writing and revising to complete the language. Available for DOS, Windows, Mac, Unix, Linux and other platforms, visit the TeX User Group at www.tug.org for more information. See LaTeX.