1 A promise, vow, or agreement to do something. 2 An order, especially one from a court, directing that a person be taken to and placed in the care or custody of a hospital, mental health facility, prison, or similar institution. civil commitment. The commitment of a person to a hospital, mental health facility, or similar institution upon a civil court's finding that the person is ill, incompetent, addicted to drugs, or in some similar circumstances and is a danger to himself or others. diag...