(psychiatry) A behavioral or mental pattern that may cause suffering or a poor ability to function in life.

plural of trench mentality

an attitude towards differences of opinion, where oppositional stand-off or conflict is preferred over debate and compromise.

plural of mental

plural of mental midget

(informal) A stupid person.

plural of mental aberration

A deviation in mental function.

(medicine) sycosis

(UK, slang) An insane person; a nutcase.