Donostia in Basque or San Sebastian in Spanish are the names of a magnificent Spanish Basque town. Are these names related some how?
Apparently the answer is yes.
Let’s take a look on what we can find in the Wikipedia:
“In spite of appearances, both the Basque form Donostia and the Spanish form San Sebastián have the same meaning of Saint Sebastian. The dona/done/doni element in Basque place-names signifies “saint” and is derived from Latin domine; the second part of Donostia contains a shortened form of the saint’s name. There are two hypothesis regarding the evolution of the Basque name: one says it was *Done Sebastiáne > Donasa(b)astiai > Donasastia > Donastia > Donostia, the other one says it was *Done Sebastiane > *Done Sebastiae > *Done Sebastie > *Donesebastia > *Donasastia > *Donastia > Donostia.”