• Mental illness is a broad, generic label for a category of illnesses that may include affective or emotional instability, behavioral dysregulation, cognitive dysfunction or impairment. Specific illnesses known as mental illnesses include major depression, generalized anxiety disorders, schizophrenia, and attention deficit hyperactivity disorder, to name a few. Mental illness can be of biological (e.g., anatomical, chemical, or genetic) or psychological (e.g., trauma or conflict) origin. It can impair the affected person's ability to work or study and can harm interpersonal relationships. The term insanity is used technically as a legal term.

An organic disease is one caused by a physical or physiological change to some tissue or organ of the body. The term sometimes excludes infections. It is commonly used in contrast with mental disorders. It includes emotional and behavioral disorders if they are due to changes to the physical structures or functioning of the body, such as after a stroke or a traumatic brain injury, but not if they are due to psychosocial issues.

• Progressive disease
  • Progressive disease is a disease whose typical natural course is the worsening of the disease until death, serious debility, or organ failure occurs. Slowly progressive diseases are also chronic diseases; many are also degenerative diseases. The opposite of progressive disease is stable disease or static disease: a medical condition that exists, but does not get better or worse.

• Acute disease
  • An acute disease is a short-lived disease, like the common cold.
• Chronic disease
  • A chronic disease is one that lasts for a long time, usually at least six months. During that time, it may be constantly present, or it may go into remission and periodically relapse. A chronic disease may be stable (does not get any worse) or it may be progressive (gets worse over time). Some chronic diseases can be permanently cured. Most chronic diseases can be beneficially treated, even if they cannot be permanently cured.

• Clinical disease
  • One that has clinical consequences; in other words, the stage of the disease that produces the characteristic signs and symptoms of that disease.AIDS is the clinical disease stage of HIV infection.
• Refractory disease
  • A refractory disease is a disease that resists treatment, especially an individual case that resists treatment more than is normal for the specific disease in question.
• Subclinical disease
  • Also called silent disease, silent stage, or asymptomatic disease. This is a stage in some diseases before the symptoms are first noted.[22]
• Terminal phase
  • If a person will die soon from a disease, regardless of whether that disease typically causes death, then the stage between the earlier disease process and active dying is the terminal phase.

• Localized disease
  • A localized disease is one that affects only one part of the body, such as athlete's foot or an eye infection.
• Disseminated disease
  • A disseminated disease has spread to other parts; with cancer, this is usually called metastatic disease.
• Systemic disease
  • A systemic disease is a disease that affects the entire body, such as influenza or high blood pressure.