Possibly derived from Latin
bonus, -
a, -
um meaning "good, kind, pleasant, right, honest, brave, noble; valid, useful, healthy". This was the name of a 12th-century Italian saint. Shakespeare also used it for a character, the sister of the king of France, in
Henry VI, Part 3 (1591). He based the character on the 15th-century duchess Bona of Savoy, a sister-in-law of King Louis XI (through her sister Charlotte, who became his second wife).