Where does “ฉันใด” come from?

ฉันใด (Thai) comes from Thai ใด, from Proto-Tai ɗaɰᴬ — which.

ฉันใด (Thai): how; in what/which manner; in what/which way; by...

Definitions

Step	Language	Word	Meaning
1	Thai	ใด	any; which
2	Proto-Tai	ɗaɰᴬ	which

ฉันใด — Etymology, Origin & Word History | Etymology Explorer