Source : Webster's Revised Unabridged Dictionary (1913)

Somnambulism \Som*nam"bu*lism\, n. [Cf. F. somnambulisme. See
   {Somnambulation}.]
   A condition of the nervous system in which an individual
   during sleep performs actions approppriate to the waking
   state; a state of sleep in which some of the senses and
   voluntary powers are partially awake; noctambulism.

Source : WordNet®

somnambulism
     n : walking by a person who is asleep [syn: {sleepwalking}, {somnambulation},
          {noctambulism}, {noctambulation}]