PLETHYSMOGRAPH

[ple.thys.mo.graph] n [ISV, fr. Gk plethysmos increase, fr. plethynein to increase, fr. plethys mass, quantity, fr. plethein] (1872): an instrument for determining and registering variations in the size of an organ or limb resulting from changes in the amount of blood present or passing through it -- ple.thys.mo.graph.ic adj -- ple.thys.mo.graph.i.cal.ly adv -- pleth.ys.mog.ra.phy n