Cyrillic
Concise Oxford English Dictionary © 2008 Oxford University Press:
Cyrillic /sɪˈrɪlɪk/
▶adjective denoting the alphabet used by many Slavic peoples, chiefly those with a historical allegiance to the Orthodox Church; now used especially for Russian and Bulgarian. ▶noun the Cyrillic alphabet.
– origin C19: named after the 9th-cent. Greek missionary St Cyril, its reputed inventor.
'Cyrillic' also found in these Oxford entries:

