Cyanosis: A bluish color of the skin and the mucous membranes due to insufficient oxygen in the blood. For example, the lips can develop cynanosis when exposed to extreme cold. Cyanosis can be present at birth, as in a 'blue baby,' an infant with a malformation of the heart that permits into the arterial system blood that is not fully oxygenated.
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Last Editorial Review: 5/13/2016