WordNet (r) 3.0 (2006):

quantum mechanics
    n 1: the branch of quantum physics that accounts for matter at
         the atomic level; an extension of statistical mechanics
         based on quantum theory (especially the Pauli exclusion
         principle)

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "quantum mechanics":
   aeromechanics, animal mechanics, atomic science, atomics,
   atomistics, atomology, biomechanics, celestial mechanics,
   electromechanics, fluid mechanics, frequency curve,
   frequency distribution, game theory, hydromechanics, leverage,
   mass spectrography, mass spectrometry, mathematical probability,
   mechanical arts, mechanics, molecular physics, nuclear chemistry,
   nuclear physics, operations research, predictability,
   probability theory, probable error, radiology, rational mechanics,
   servomechanics, standard deviation, statistical mechanics,
   statistical probability, statistics, thermionics,
   uncertainty principle, wave mechanics, zoomechanics