Where does “mwst” come from?

mwst (Welsh) comes from Middle English must, from Old French must, from Latin mustum, from Latin mustus, from Proto-Indo-European mūs- — fly, stinging fly, gnat; moist, damp; swamp,...

mwst (Welsh): must fermented grape juice

Definitions

must fermented grape juice

Ancestry of “mwst”, step by step

Step	Language	Word	Meaning
1	Middle English	must	must wine that is not fully fermented
2	Old French	must	—
3	Latin	mustum	must; unfermented or partially fermented grape...
4	Latin	mustus	fresh, young; unfermented
5	Proto-Indo-European	mūs-	fly, stinging fly, gnat; moist, damp; swamp,...

Every word from Proto-Indo-European mūs- →Every word from Latin mustus →Every word from Latin mustum →