Where does “duodecapolis” come from?

duodecapolis (English) comes from English -polis, from Latin -polis, from Ancient Greek πόλις, from Proto-Hellenic ptólis, from Proto-Indo-European tpólHis, from Proto-Indo-European tpelH- — fortification, city.

Ancestry of “duodecapolis”, step by step

StepLanguageWordMeaning
1English-polisForms names of cities
2Latin-polisForms names of cities
3Ancient Greekπόλιςcity; a whole country, as dependent on and called...
4Proto-Hellenicptóliscity
5Proto-Indo-EuropeantpólHis—
6Proto-Indo-EuropeantpelH-fortification, city
Every word from Proto-Indo-European tpelH- →Every word from Proto-Indo-European tpólHis →Every word from Proto-Hellenic ptólis →