any of various skin diseases characterized by the shedding of scaly
flakes of epidermis
a skin disease of domestic animals, characterized by the formation
of dry scales
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'pityriasis'ModL < Gr < pityrion, bran, scale