Neurosis

[,njʊə'rəʊsɪs] or [nʊ'rosɪs]

(noun.) a mental or personality disturbance not attributable to any known neurological or organic dysfunction.

Inputed by Addie--From WordNet

(n.) A functional nervous affection or disease, that is, a disease of the nerves without any appreciable change of nerve structure.

Checker: Mortimer