| plethysmograph | (n) a measuring instrument for measuring changes in volume of a part or organ or whole body (usually resulting from fluctuations in the amount of blood it contains) |
| Plethysmograph | ‖n. [ Gr. &unr_; an enlargement + -graph. ] (Physiol.) An instrument for determining and registering the variations in the size or volume of a limb, as the arm or leg, and hence the variations in the amount of blood in the limb. [ 1913 Webster ] -- |
| Plethysmography | n. (Physiol.) The study, by means of the plethysmograph, of the variations in size of a limb, and hence of its blood supply. [ 1913 Webster ] |