Where does “swahili” come from?

swahili (Swahili) comes from Arabic سَوَاحِل, from Arabic سَاحِل — coast; boundary, coast; border of the desert.

Ancestry of “swahili”, step by step

Step	Language	Word	Meaning
1	Arabic	سَوَاحِل	coastal dwellers
2	Arabic	سَاحِل	coast; boundary, coast; border of the desert