Where does “muay” come from?

muay (English) comes from Thai มวย, from Sanskrit मव्यति — to bind.

Ancestry of “muay”, step by step

Step	Language	Word	Meaning
1	Thai	มวย	boxing; fisticuffs; fistfight; pugilism; knot;...
2	Sanskrit	मव्यति	to bind

muay — Etymology, Origin & Word History | Etymology Explorer