/pit'euh ruy"euh sis/ , n.
1. Pathol. any of various skin diseases marked by the shedding of branlike scales of epidermis.
2. Vet. Pathol. a skin disease in various domestic animals marked by dry scales.
[ 1685-95; pityríasis branlike eruption, equiv. to pítyr ( on ) bran, scale + -iasis -IASIS ]