Where does “Niğbolu” come from?

Niğbolu (Turkish) comes from Ottoman Turkish نیگبولی, from Bulgarian Никопол, from Ancient Greek Νικόπολις, from Ancient Greek πόλις, from Proto-Hellenic ptólis, from Proto-Indo-European tpólHis, from Proto-Indo-European tpelH- — fortification, city.

Ancestry of “Niğbolu”, step by step

Step	Language	Word	Meaning
1	Ottoman Turkish	نیگبولی	—
2	Bulgarian	Никопол	—
3	Ancient Greek	Νικόπολις	city of victory
4	Ancient Greek	πόλις	city; a whole country, as dependent on and called...
5	Proto-Hellenic	ptólis	city
6	Proto-Indo-European	tpólHis	—
7	Proto-Indo-European	tpelH-	fortification, city

Every word from Proto-Indo-European tpelH- →Every word from Proto-Indo-European tpólHis →Every word from Proto-Hellenic ptólis →