PLETHYSMOGRAPH

plethysmograph

(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)

Source: WordNet® 3.1

Etymology

Late 19th century: from Greek plēthusmos ‘enlargement’ (based on plēthus ‘fullness’) + -graph.

Noun

plethysmograph (plural plethysmographs)

(medicine) An instrument for measuring changes in volume within an organ or whole body (usually via fluctuations in the amount of fluid it contains).

Source: Wiktionary

Pleth"ys*mo*graph, n. Etym: [Gr. -graph.] (Physiol.)

Definition: 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.

Source: Webster’s Unabridged Dictionary 1913 Edition