Source : Webster's Revised Unabridged Dictionary (1913)

Neurosis \Neu*ro"sis\, n.; pl. Neuroses. [NL., fr. gr. ? nerve.]
   (Med.)
   A functional nervous affection or disease, that is, a disease
   of the nerves without any appreciable change of nerve
   structure.

Source : WordNet®

neurosis
     n : a mental or personality disturbance not attributable to any
         known neurological or organic dysfunction [syn: {neuroticism},
          {psychoneurosis}]
     [also: {neuroses} (pl)]