Oona is an anglicized spelling of the Irish Úna, a name of uncertain origin that is usually explained as "lamb", from the Irish uan, or linked to the Latin una, "one". Oona O'Neill, daughter of playwright Eugene O'Neill and wife of Charlie Chaplin, gave the spelling a glamorous association. Oona is rare in the United States, peaking at number 1639 in 2015 and ranking number 2768 in 2025.