<p><strong>Adjective:</strong></p><ul><li>of or relating to the mind (e.g., mental powers; mental suffering)</li><li>of, relating to, or affected by a disorder of the mind (e.g., a mental patient; mental illness)</li><li>providing care for persons with disordered minds, emotions, etc. (e.g., a mental hospital)</li><li>performed by or existing in the mind (e.g., mental arithmetic; a mental note)</li><li>pertaining to intellectuals or intellectual activity</li><li>Informal: slightly daft; out of one's mind; crazy (e.g., He's mental)</li></ul><p><strong>Noun (Informal):</strong></p><ul><li>a person with a psychological disorder (e.g., a fascist group made up largely of mentals)</li></ul>