Where does “ܫܪܫܐ” come from?

ܫܪܫܐ (Classical Syriac) comes from Aramaic שֻׁרְשׁא, from Proto-Semitic *šurš- — root, wort.

ܫܪܫܐ (Classical Syriac): root; ground, base, foundation; ball of thread or...