Where does “ซ้ำ” come from?

ซ้ำ (Thai) comes from Proto-Tai zamᶜ — to repeat.

ซ้ำ (Thai): repeated; duplicated; repeatedly; again; to...

Definitions

Step	Language	Word	Meaning
1	Proto-Tai	zamᶜ	to repeat

ซ้ำ — Etymology, Origin & Word History | Etymology Explorer