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Medical Term:


Pronunciation: to-nom'e-ter


  1. An instrument for determining pressure or tension, especially an instrument for determining ocular tension.
  2. A vessel for equilibrating a liquid (blood) with a gas, usually at a controlled temperature; originally so named because it was used with a low gas:blood ratio to allow the gas to approach blood oxygen tension and thus serve as a measure of it; now commonly used with a high gas:blood ratio to adjust the blood to the oxygen pressure of the gas.

Synonym(s): aerotonometer2

[tono- + G. metron, measure]

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