Where does “Greekism” come from?

Greekism (English) comes from English greek, from Old English Grēcas, from Esperanto kreko, from Latin Graecus, from Ancient Greek Γραικός, from Ancient Greek γραῖα, from Proto-Indo-European ǵerh₂- — to grow old, to mature.

Ancestry of “Greekism”, step by step

Greekism traces back through two separate lines of ancestry.

via English greek

Step	Language	Word	Meaning
1	English	greek	Alternative letter-case form of Greek; To display...
2	Old English	Grēcas	the Greeks; Greeks
3	Esperanto	kreko	teal
4	Latin	Graecus	Greek, Grecian, of or pertaining to the Greek...
5	Ancient Greek	Γραικός	Greek; a Graecian, a member of an ancient...
6	Ancient Greek	γραῖα	Graea, Boeotia; Greece
7	Proto-Indo-European	ǵerh₂-	to grow old, to mature

via English ism

Step	Language	Word	Meaning
1	English	ism	An ideology, system of thought, or practice that...
2	English	-ism	Used to form nouns of action or process or result...
3	Latin	-ismus	-ism
4	Ancient Greek	-ισμός	Forms abstract nouns
5	Ancient Greek	-μός	Forms abstract nouns
6	Proto-Indo-European	-mós	Creates action/result nouns from verb stems

Every word from Proto-Indo-European ǵerh₂- →Every word from Ancient Greek γραῖα →Every word from Ancient Greek Γραικός →