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Noun. 1. induration-any pathological hardening or thickening of tissue. sclerosis. disseminated multiple sclerosis, disseminated sclerosis, MS, multiple sclerosis-a chronic progressive nervous disorder involving loss of myelin sheath around certain nerve fibers.
Medical Definition of INVAGINATION. 1. : an act or process of invaginating: as a: the formation of a gastrula by an infolding of part of the wall of the blastula b: intestinal intussusception.2. : an invaginated part.edical Definition of INVAGINATION. 1. : an act or process of invaginating: as a: the formation of a gastrula by an infolding of part of the wall of the blastula b: intestinal intussusception. 2.