Where does “ไหม้” come from?

ไหม้ (Thai) comes from Proto-Tai ʰmajᶜ — to burn.

ไหม้ (Thai): to burn; burnt

Definitions

Step	Language	Word	Meaning
1	Proto-Tai	ʰmajᶜ	to burn

ไหม้ — Etymology, Origin & Word History | Etymology Explorer