The name Oona is a girl's name of Irish origin meaning "lamb". Oona and is often added to lists like Unique Vintage Baby Names for Girls and discussed in our forums with posts like "A brother or sister for little Jack or Olivia".
From the experts:
Oona is a name made famous by Eugene O'Neill's daughter, who became Charlie Chaplin's wife. One of the original Oona's granddaughters was named after her, and is now an actress famous in her own right for playing Talisa of Volantis in HBO's "Game of Thrones." The double-o beginning gives their name a lot of oomph.
In Irish legend, Una/Oona was a daughter of a king of Lochlainn. The name was very popular in Ireland in the Middle Ages, and is currently seeing a comeback--also spelled Oonagh.