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Pronunciation: re-zis'tans


  1. A force exerted in opposition to an active force.
  2. The opposition in a conductor to the passage of a current of electricity, whereby there is a loss of energy and a production of heat; specifically, the potential difference in volts across the conductor per ampere of current flow; unit: ohm.
  3. The opposition to flow of a fluid through one or more passageways (blood flow, respiratory gases in the tracheobronchial tree), analogous to (2); units are usually those of pressure difference per unit flow.
  4. In psychoanalysis, one's unconscious defense against bringing repressed thoughts to consciousness.
  5. The ability of red blood cells to resist hemolysis and to preserve their shape under varying degrees of osmotic pressure in the blood plasma.
  6. The natural or acquired ability of an organism to maintain its immunity to or to oppose the effects of an antagonistic agent, a toxin, drug, or pathogenic microorganism.
  7. In endocrinology, a defective target tissue response to a hormone.

Synonym(s): hormone resistance

[L. re-sisto, to stand back, withstand]

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.