A term used to describe the color of a patient's skin who is not getting enough oxygen. Generally, this condition is more noticeable in people who have light or fair complexions. Cyan is a bluish green color. If the patient's blood is not being adequately oxygenated and the blood in the tissues is dark red to purple, the skin appears bluish, hence the name cyanosis. Cyanosis is sometimes seen with some congenital heart conditions.