The Free On-line Dictionary of Computing (30 December 2018):
MuTeX
    An extension of TeX for typesetting music.
   (ftp://nic.stolaf.edu/pub/mutex/MuTeX.tar.Z).
   (1995-02-06)
The Free On-line Dictionary of Computing (30 December 2018):
mutex
    A mutual exclusion object that allows multiple
   threads to synchronise access to a shared resource.  A mutex
   has two states: locked and unlocked.  Once a mutex has been
   locked by a thread, other threads attempting to lock it will
   block.  When the locking thread unlocks (releases) the mutex,
   one of the blocked threads will acquire (lock) it and proceed.
   If multiple threads or tasks are blocked on a locked mutex
   object, the one to take it and proceed when it becomes
   available is determined by some type of scheduling algorithm.
   For example, in a priority based system, the highest priority
   blocked task will acquire the mutex and proceed.  Another
   common set-up is put blocked tasks on a first-in-first-out
   queue.
   See also: priority inversion
   (2002-03-14)