In the context of a Complete Blood Count (CBC) blood test, the MCV measurement refers to "Mean Corpuscular Volume." It measures the average volume of a sample of red blood cells, and is used as a factor in diagnosing and classifying anemia and other conditions, as explained by WebMD.
According to Medscape, the reference range for MCV is 80-90 fl/red cell, though this can vary according to age and other conditions. A higher than normal MCV is a possible indicator of alcoholism, B12 deficiency and low folic acid. A low MCV is most commonly caused by an anemic iron deficiency, according to Medline.