Complex sentence: The toponym "Gradec" is relatively common in Slovenia and is derived from the Slovene common noun "gradec"'small walled settlement' (which only later developed the contemporary meaning'castle, chateau').
Split into simpler sentences: The toponym "Gradec" is relatively common in Slovenia. It is derived from the Slovene common noun "gradec"'small walled settlement' (which only later developed the contemporary meaning'castle, chateau').