Where does “Шчечин” come from?

Шчечин (Bulgarian) comes from Polish Szczecin, from Polish -in, from Latin -īnus, from Proto-Italic -īnos, from Proto-Indo-European -iHnos, from Proto-Indo-European -no- — adjectival suffix.

Ancestry of “Шчечин”, step by step

StepLanguageWordMeaning
1PolishSzczecin—
2Polish-informs nouns
3Latin-īnusof or pertaining to; -ine
4Proto-Italic-īnosof/belonging to
5Proto-Indo-European-iHnosCreates adjectives of materials
6Proto-Indo-European-no-adjectival suffix
Every word from Proto-Indo-European -no- →Every word from Latin -īnus →Every word from Proto-Italic -īnos →