Final answer:
A bluish discoloration of the skin due to low blood oxygen is known as cyanosis, which occurs when there is a restricted oxygen supply, different from conditions that cause yellowing or redness of the skin.
Step-by-step explanation:
A bluish discoloration of the skin due to low blood oxygen is known as cyanosis. This condition occurs when the oxygen supply to the body is restricted, such as during an asthma attack or a heart attack. Unlike jaundice, which gives a yellow coloration due to bilirubin accumulation, or conditions like erythema, which is redness of the skin, or pallor, which is paleness, cyanosis is linked with a reduction of oxygen in the blood leading to a blue appearance, especially noticeable in areas like the lips, nails, and skin. Addison's disease and liver problems can also lead to specific discolorations, but these occur due to hormonal changes or bilirubin accumulation, respectively, not oxygenation levels.