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Pronunciation: ak′ti-vā-tōr


  1. A substance that renders another substance (a catalyst) active, or that accelerates a process or reaction.
  2. The fragment produced by chemical cleavage of a proactivator, that induces the enzymic activity of another substance.
  3. An apparatus for making substances radioactive (a neutron generator or a cyclotron).
  4. A removable type of myofunctional orthodontic appliance that acts as a passive transmitter of force, produced by the function of the activated muscles, to the teeth and alveolar process that are in contact with it.
  5. A protein that binds to a DNA sequence before RNA polymerase transcription, sometimes referred to as coactivator.

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