plethysmograph Meaning, Definition & Usage

  1. noun 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)

WordNet

Pleth"ys*mo*graph noun
Etymology
Gr. an enlargement + -graph.
Definitions
  1. (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. -- Pleth`ys*mo*graph"ic a.

Webster 1913