Yours, Etc.: Origins and Uses of 8 Sign-Offs
late Old English sceorf, from Proto-Germanic *skurf- (cf. Danish skurv, Middle Dutch scorf, Dutch schurft, Old High German scorf, German Schorf "scurf"), probably related to Old English sceorfan "to gnaw," scearfian "to cut into shreds," from PIE *skerp-, from root *(s)ker- "to cut" (see shear (v.)).
Scaly or shredded dry skin, such as that which occurs as dandruff.