Source : WordNet®

hematocrit
     n 1: the ratio of the volume occupied by packed red blood cells
          to the volume of the whole blood as measured by a
          hematocrit [syn: {haematocrit}, {packed cell volume}]
     2: a measuring instrument to determine (usually by
        centrifugation) the relative amounts of corpuscles and
        plasma in the blood [syn: {haematocrit}]