An Etymological Dictionary of the German Language/schleichen
schleichen, vb., ‘to creep, crawl, slink,’ from MidHG. slîchen, OHG. slîhhan, ‘to walk with a light sliding motion, creep’; ‘akin to MidHG. slī̆ch, m., ‘slime, mud,’ Du. slik, slijk, ‘slime, mud,’ MidE. slîken, ‘to creep,’ with which E. sleek and slick are connected; in the other languages the Teut. root slī̆k (pre-Teut. slī̆g) rarely occurs. — To this is allied Schleiche in Blindschleiche, f., ‘blind-worm,’ MidHG. blintslîche, OHG. blintslîcho, m. See Schlich.