Where does “Roterdamo” come from?

Roterdamo (Esperanto) comes from Dutch Rotterdam, from Middle Dutch rotterdam, from Middle Dutch dam, from Old Dutch dam, from Proto-West Germanic *damm, from Proto-Germanic dammaz — dam.

Ancestry of “Roterdamo”, step by step

StepLanguageWordMeaning
1DutchRotterdam—
2Middle DutchrotterdamRotterdam
3Middle Dutchdam—
4Old Dutchdam—
5Proto-West Germanic*dammdam
6Proto-Germanicdammazdam
Every word from Proto-Germanic dammaz →Every word from Proto-West Germanic *damm →Every word from Old Dutch dam →