Source : Webster's Revised Unabridged Dictionary (1913)

Somnambulation \Som*nam`bu*la"tion\, n. [L. somnus sleep +
   ambulatio a walking about, from ambulare to walk. See
   {Somnolent}, {Amble}.]
   The act of walking in sleep.

Source : WordNet®

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