Hematocrit

n. centrifuge for separating blood cells from plasma; relationship between the volume of cells and the volume of blood separated by a centrifuge

The hematocrit (Ht or HCT) or packed cell volume (PCV) are measures of the proportion of blood volume that is occupied by red blood cells. It is normally 45 ± 7 (38-52%) for males and 42 ± 5 (37-47%) for females.The packed cell volume can be determined by centrifuging. Heparinized blood in a capillary tube (also known as a microhematocrit tube) is typically centrifuged at 10,000 RPM for five minutes.[1] This separates the blood into layers. The volume of packed red blood cells, divided by the total volume of the blood sample gives the PCV. Because a tube is used this can be calculated by measuring the lengths of the layers.
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The hematocrit measures how much space in the blood is occupied by red blood cells. [more]Hematocrit - Community and Resources

Noun
1. the ratio of the volume occupied by packed red blood cells to the volume of the whole blood as measured by a hematocrit
(synonym) haematocrit, packed cell volume
(hypernym) ratio
2. a measuring instrument to determine (usually by centrifugation) the relative amounts of corpuscles and plasma in the blood
(synonym) haematocrit
(hypernym) measuring instrument, measuring system, measuring device

The percentage, by volume, of red cells in blood. Normal range for males is about 40-54 and for females 37-47 (values may vary slightly between laboratories).