Haematocrits

Part of speech: noun

Definitions

1. The percentage of the total blood volume made up of red blood cells, measured as a clinical indicator of anemia or dehydration
2. The share of whole blood taken up by erythrocytes, commonly reported in medical tests to assess a patient's oxygen-carrying capacity
3. A laboratory measure expressing how much of a blood sample consists of red cells, used to help diagnose conditions affecting circulation

Etymology: "Haematocrits" is simply the plural of "haematocrit," a noun for the proportion of blood volume occupied by red blood cells. The base word is a modern scientific coinage built from classical Greek parts: "haima" (blood) and "krites," meaning a judge or separator, the same root found in "critic" and "criterion." The sense is literal: a centrifuge spins blood so that its components separate, and the measure of how much of it is cells is what the term names. Because the word is a technical coinage, it was not used by the ancient Greeks, who had no concept of measuring blood cells. Its formation follows the pattern of earlier scientific compounds, drawing on Greek vocabulary to name a newly observed quantity. The plural simply counts several such measurements, as when a clinician compares results across patients or across several draws from one patient.

Synonyms: packed cell volume, PCV