pityriasis, n. [NL., fr. Gr. , fr. , lit., bran.].
∥Pityriasis versicolor [NL.] (Med.), a parasitic disease of the skin, characterized by the development of reddish or brownish patches.
A superficial affection of the skin, characterized by irregular patches of thin scales which are shed in branlike particles. [1913 Webster]
A disease of domestic animals characterized by dry epithelial scales, and due to digestive disturbances and alteration of the function of the sebaceous glands. [Webster 1913 Suppl.]