#dilation__dilatation  the act of expanding an aperture; "the dilation of the pupil of the eye"
  supertype:  expansion__enlargement  the act of increasing in size or volume or quantity or scope
  subtype:  vasodilation  dilation of blood vessels (especially the arteries)
  subtype:  mydriasis__mydriasi  reflex pupillary dilation as a muscle pulls the iris outward; occurs in response to a decrease in light or certain drugs

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