Where does “*lɤkᴰˢ⁴” come from?

*lɤkᴰˢ⁴ (Proto-Southwestern Tai) comes from Proto-Tai lɤkᴰ — deep.

Ancestry of “*lɤkᴰˢ⁴”, step by step

Step	Language	Word	Meaning
1	Proto-Tai	lɤkᴰ	deep

*lɤkᴰˢ⁴ — Etymology, Origin & Word History | Etymology Explorer