Where does “Thermopylen” come from?

Thermopylen (German) comes from Latin Thermopylae, from Ancient Greek Θερμοπύλαι, from Ancient Greek θερμο-, from Ancient Greek θερμός, from Ancient Greek σφαῖρα, from Ancient Greek -ειδής, from Ancient Greek -ής, from Proto-Indo-European -ēs — Creates action nouns or result nouns from verbs;...

Ancestry of “Thermopylen”, step by step

Step	Language	Word	Meaning
1	Latin	Thermopylae	—
2	Ancient Greek	Θερμοπύλαι	—
3	Ancient Greek	θερμο-	Used to derive words relating to warmth, heat;...
4	Ancient Greek	θερμός	warm, hot, boiling, glowing; hotheaded, hasty,...
5	Ancient Greek	σφαῖρα	ball, globe, sphere
6	Ancient Greek	-ειδής	like, connected to, from the nature of, full of;...
7	Ancient Greek	-ής	adjective suffix
8	Proto-Indo-European	-ēs	Primarily forms adjectival bahuvrīhi compounds
9	Proto-Indo-European	-ess	—
10	Proto-Indo-European	-os	Creates action nouns or result nouns from verbs;...

Every word from Proto-Indo-European -os →Every word from Ancient Greek -ειδής →Every word from Ancient Greek σφαῖρα →