"pertaining to Greece," 1640s, from Greek Hellēnikos "Hellenic, Greek," from Hellēn "a Greek," a word of unknown origin; traditionally from the name of an eponymous ancestor, Hellēn, son of Deucalion. To Homer the Hellenes were a small tribe in southern Thessaly (his word for one of the Greek-speaking peoples is our Achaean). In modern use in the arts, Hellenic is used of Greek work from the close of the primitive phase to the time of Alexander the Great or the Roman conquest (succeeded by the Hellenistic).
word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.
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<a href="https://www.etymonline.com/word/Hellenism">Etymology of Hellenism by etymonline</a>
Harper, D. (n.d.). Etymology of Hellenism. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/Hellenism