hair side meaning in Information Science terminology / glossary / dictionary is:
The side of a sheet of parchment or vellum to which the animal’s hair was once attached. Generally darker in color and smoother in texture than the flesh side, the hair side can be distinguished by the presence of tiny flecks at the location of the hair follicles. In medieval manuscripts, the sheets were gathered with hair side facing hair side and flesh side facing flesh side, so that the right and left sides of an opening (recto and verso) were of the same color. Click here to see the difference in color and texture between the hair and flesh side in successive openings in a 13th-century English bestiary, courtesy of the Royal Library of Denmark.