An Etymological Dictionary of the German Language/Annotated/Speichel
Speichel, masculine, ‘spittle, saliva,’ from the equivalent Middle High German speichel, Old High German speihhilla, speihhila, feminine; allied to Dutch speeksel (Gothic *spaikuldr?), ‘spittle.’ It is uncertain in what way these cognates are connected with the root spîw, ‘to spit’ (see speien and spucken).