An Etymological Dictionary of the German Language/Annotated/Unschlitt
Unschlitt, Inschlitt (Inselt), neuter, ‘suet, tallow,’ from Middle High German unslit (unselt), inslit (inselt), neuter, ‘tallow,’ of which there are abundant variants in Middle High German. Compare Old High German unslit, ‘fat, tallow’ (Anglo-Saxon unslid, or rather unflid, ‘fat, grease, tallow,’ is uncertain). Middle High German unsleht, ‘tallow’ (Rhenish-Franconian inschlicht), seems to be connected with Middle High German (in)geslehte, neuter, ‘entrails.’ The derivation of the word cannot be more definitely determined, since the older forms are unknown; Hessian and Low German ungel, ‘tallow,’ suggests the supposition that Old High German unslit has originated in *ungslit.