ἀρχαῖος
Etym. ἀρχή 1
"from the beginning":
I. of things, "ancient, primeval, olden", Hdt., attic
2. like ἀρχαϊκός, "old-fashioned, antiquated, primitive", Aesch., Ar.
3. "ancient, former", τὸ ἀρχ. ῥέεθρον Hdt., etc.
II. of persons, "ancient, old", Aesch., Thuc., etc.: οἱ ἀρχαῖοι "the Ancients, the old Fathers, Prophets", NTest.
III. adv. ἀρχαίως, "anciently", Dem.; so, τὸ ἀρχαῖον, ionic contr. τὠρχαῖον Hdt., attic τἀρχαῖον Aesch.
2. "in olden style", Plat., Aeschin.
IV. as Subst., τὸ ἀρχαῖον, "the original sum, the principal", Lat. sors, Ar., Oratt.