Where does “ترس” come from?

ترس (South Levantine Arabic) comes from Arabic تُرْس, from Ancient Greek θυρεός, from Ancient Greek θῠ́ρᾱ, from Proto-Indo-European dʰwer- — door.

ترس (South Levantine Arabic): shield

Definitions

Step	Language	Word	Meaning
1	Arabic	تُرْس	shield
2	Ancient Greek	θυρεός	a stone put against a door to keep it shut, a...
3	Ancient Greek	θῠ́ρᾱ	door, entrance
4	Proto-Indo-European	dʰwer-	door