Cyanosis: A bluish color of the skin and the mucous membranes due to insufficient oxygen in the blood.
Pallor: paleness, as of the skin or mucosae. Although it is commonly associated with anemia, many long-term cases show mucosae of normal color; pallor is also a common sign in shock.
Pallor may result from diminished peripheral blood flow associated with peripheral vasoconstriction, arterial occlusion, or low cardiac output. (Transient peripheral vasoconstriction may occur with exposure to cold, causing nonpathologic pallor.) The latter usually results from anemia.