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Pronunciation: ak′ti-vā′shŭn


  1. The act of rendering active.
  2. An increase in the energy content of an atom or molecule, effected by means such as increased temperature or absorption of light photons that renders that atom or molecule more reactive.
  3. Techniques of stimulating the brain by light, sound, electricity, or chemical agents, to elicit abnormal activity in the electroencephalogram.
  4. Stimulation of peripheral nerve fibers to the point that action potentials are initiated.
  5. Stimulation of cell division in an oocyte by fertilization or by artificial means.
  6. The act of making radioactive.

See Also: cross-section

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