(1) (MUTually EXclusive) A programming flag used to grab and release an object. When data are acquired that cannot be shared or processing is started that cannot be performed simultaneously elsewhere in the system, the mutex is set to "lock," which blocks other attempts to use it. The mutex is set to "unlock" when the data are no longer needed or the routine is finished. See flag.

(2) (MUsic TEX) A package of macros for the TeX typesetting system that supports musical notation.