Where does “ʼaṃmnāja” come from?

ʼaṃmnāja (Old Khmer) comes from Old Khmer ʼāca.

Ancestry of “ʼaṃmnāja”, step by step

Step	Language	Word	Meaning
1	Old Khmer	ʼāca	—

ʼaṃmnāja — Etymology, Origin & Word History | Etymology Explorer