from
The Collaborative International Dictionary of English v.0.48
Pityriasis \Pit`y*ri"a*sis\, n. [NL., fr. Gr. ?, fr. ?, lit.,
bran.]
1. (Med.) A superficial affection of the skin, characterized
by irregular patches of thin scales which are shed in
branlike particles.
[1913 Webster]
2. (Veter.) 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.]
{Pityriasis versicolor} [NL.] (Med.), a parasitic disease of
the skin, characterized by the development of reddish or
brownish patches.
[1913 Webster]