Baby Names of Ireland

Irish Names Starting with O

7 Irish names beginning with O for girls and boys, with what each one means and how to say it.

Updated September 2026

Of the 7 Irish names starting with O here, 3 are for girls and 4 for boys. The ones readers look up most are Oisin, Owen and Orla.

The O names on this page that the most babies were given in 2025, by the Central Statistics Office’s ranking (girls and boys are ranked separately).

  1. No. 5 boysOisín331 babies
  2. No. 93 boysOdhrán63 babies
  3. No. 325 girlsÓrlaith12 babies

Irish girl names starting with O

Oonagh

pronounced OU-na

From the Irish word uan “a lamb” or may come from the Latin una meaning “one,” hence it is sometimes translated as “Unity.”

More about Oonagh

Orlaith

pronounced OR-la

Orlaith comes from the Irish Órlaith (older Órfhlaith), from ór “gold” and flaith “ruler, prince,” which is read as “princess” in women’s names, so “golden princess.”

More about Orlaith

Irish boy names starting with O

Odhran

pronounced O-ran

All variants of odhra meaning “dark haired.” Seventeen saints have used the name and Odhran, abbot of Meath, was one of the 12 devotees who accompanied St. Columba to Iona.

More about Odhran

Oisin

pronounced osh-EEN

The son of the legendary warrior Fionn Mac Cool and the goddess Sive. His mother was turned into a deer by the Dark Druid and she reared him in the forest until he was seven years old.

More about Oisin

Owen in Irish is Eoghan, pronounced O-in, meaning “born of the yew tree.”

More about Owen

Irish names by letter

More Irish name lists