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Medical Term:


Pronunciation: kros′sek′shŭn


  1. A transverse section through a structure.
  2. A planar section through a structure in any plane; a two-dimensional slice through an anatomic structure.
  3. The probability of an activation (q.v., sense 5) by a nuclear reaction when a material is bombarded by neutrons, as in the production of radionuclides in a pile; unit: barn (10−24 cm2/atom).