Where does “Dulce” come from?

Dulce (Spanish) comes from Spanish dulce, from Latin dulcis, from Proto-Indo-European dl̥kú- — sweet.

Ancestry of “Dulce”, step by step

Step	Language	Word	Meaning
1	Spanish	dulce	sweet; fresh; candy, sweet
2	Latin	dulcis	sweet; sweet-smelling, sweet-scented, fragrant;...
3	Proto-Indo-European	dl̥kú-	sweet

Dulce — Etymology, Origin & Word History | Etymology Explorer