de·dif·fer·en·ti·a·tion (dē'dĭf-ə-rěn'shē-ā'shən) n.
Biology Regression of a specialized cell or tissue to a simpler, more embryonic, unspecialized form. Dedifferentiation may occur before the regeneration of appendages in plants and certain animals and in the development of some cancers. de'dif·fer·en'ti·ate' v.