designating or of the Slavic alphabet traditionally attributed to Saint Cyril, 9th cent. apostle to the Slavs: in modified form, it is still used in Russia, Bulgaria, and other Slavic countries
See Cyrillic in American Heritage Dictionary 4
Cy·ril·lic
adjective
Of or being any of the alphabets based on Glagolitic and used for certain Slavic languages, such as Russian.
Origin: Invention incorrectly attributed to Saint Cyril.