Jagiellon
The aristocratic name Jagiellon looks like it is a transcription of Semitic אגי עליון ˀgy-ˁlywn, which means “highest saint” or “highest aristocrat”.
עליון ˁlywn elion is a very common Semitic word meaning “exhalted” & “supreme”, and would be pronounced like the -ellon part of Jagiellon.
אגא ˀgˀ aga is a Turkish term for “lord” & “master”, which has been loaned into various other languages, including Aramaic. In Aramaic grammar, it can be prefixed & suffixed with Y, which would make it sound like the Jagi- part of Jagiellon. Greek ἅγιος agios for “saint” and ἄγω ago for “leader” may also be related.
Aramaic, Turkish, Greek ˀgˀ = lord, master, noble, saint; ˁly = top, highest
אגי ˀgy : saint, saints; Greek ἅγιος — Aramaic (CAL)
אגיא ˀgyˀ : nobles, notables; from Turkish — Aramaic (CAL)
aga : big brother; rich man; From Ottoman Turkish آغا (aghā) — Turkish (Wikt)
آغا ağa : lord, master; head of household; honorific title of address, Mr., sir; title of various military and civil officers — Ottoman Turkish (Wikt)
آغا āġā : Mr., sir, gentleman; master; owner; lord — Urdu (Wikt)
עליו ˁlyw : superiority, majesty; upper part — Aramaic (CAL)
עליון ˁlywn : most high one — Aramaic (CAL)
These languages were not officially spoken in the areas where the Jagiellons reigned. But since ties from the Byzantine “church” to all Slavic empires are officially admitted, it’s not hard to imagine that the owners of these regions originally came from Byzantium.
The official meaning of Jagiellon is “strong rider”. Ridiculous.