Loco and Mentally ill

Loco adjective - Having or showing a very abnormal or sick state of mind.

Mentally ill and loco are semantically related in sane topic. In some cases you can use "Mentally ill" instead an adjective "Loco", when it comes to topics like insane.

Mentally ill adjective - Suffering from severe mental illness.

Loco and mentally ill are semantically related in sane topic. You can use "Loco" instead an adjective phrase "Mentally ill", if it concerns topics such as unwell in the mind.