An Etymological Dictionary of the German Language/Scharbock
Scharbock, m., ‘scurf, scurvy,’ early ModHG., a corruption of MidLat. scorbûtus. From the same source are derived the equiv. Du. scheurbuik, E. scurvy, Ital. scorbuto, and Fr. scorbut. The ultimate source of the cognates is Du. scheurbuik, or rather its older forms with a dental in the suffix, as in scorbutus (Du. scheur, ‘rift, cleft,’ but, ‘bone’); ModDu. scheurbuik is also very probably a corruption, the word being connected with buik, ‘belly.’