Where does “ngáp” come from?

ngáp (Muong) comes from Proto-Vietic s-ŋaːp, from Proto-Mon-Khmer sʔaap — to yawn.

ngáp (Muong): to yawn

Definitions

Step	Language	Word	Meaning
1	Proto-Vietic	s-ŋaːp	—
2	Proto-Mon-Khmer	sʔaap	to yawn

ngáp — Etymology, Origin & Word History | Etymology Explorer