There are a few reasons why someone might choose to name their daughter Oonagh. One reason could be that they are of Irish descent and wanted to give their child a name that was steeped in Irish history and culture. Another possibility is that the person simply likes the sound of the name Oonagh. It is also possible that they were inspired by the legend of Queen Maeve, who was also known as Onacha or Eochaidh Uaithne. Whatever the reason, it is clear that naming one's daughter Oonagh can be seen as a meaningful and significant choice.