Where does “phrātria” come from?

phrātria (Latin) comes from Ancient Greek φρατρία, from Ancient Greek φρᾱ́τηρ — clansman, kinsmen.

Ancestry of “phrātria”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	φρατρία	brotherhood; tribe, clan; political subdivision...
2	Ancient Greek	φρᾱ́τηρ	clansman, kinsmen