An Etymological Dictionary of the German Language/Annotated/Schleim
Schleim, masculine, ‘slime, mucus, phlegm, filth,’ from Middle High German slîm, masculine, ‘slime, mire, sticky fluid’; Old High German *slîm is wanting. Compare Dutch slijm, ‘slime,’ Anglo-Saxon slîm, and the equivalent English slime, Old Icelandic slîm, neuter; Gothic *sleims is wanting. The root slī̆, ‘to be smooth, slippery,’ contained in these words, which is especially apparent in Old High German slîmen, ‘to male smooth, brighten by grinding,’ is closely related to Latin lîmare, ‘to file, polish, smooth,’ lîma, ‘file,’ with which probably Latin lêvis and Greek λεῖος, ‘smooth,’ are also connected. In Latin and Greek initial s disappears before l. Perhaps Latin lîmus, ‘slime’ (see under Lehm), may be adduced here; compare further Schleie.