Examples from the Web for ciao
I believe the word is derived from “schiavo,” a slave, which became corrupted into “schiao,” and “ciao.”Selections from Previous Works|Samuel Butler
British Dictionary definitions for ciao
Word Origin and History for ciao
parting salutation, 1929, dialectal variant of Italian schiavo "(your obedient) servant," literally "slave," from Medieval Latin sclavus "slave" (see slave (n.)).