The name Deirdre is of Irish Gaelic origin and has its roots in the Early Medieval era. It is derived from the Old Irish words "der" meaning "daughter" and "drae" meaning "wanderer" or "rover." The name can be interpreted to mean "daughter of the wanderer" or "wandering daughter."

One of the earliest and most famous references to the name Deirdre is found in the Irish legend of the Tragic Romance, which dates back to the 8th century AD. In this tale, Deirdre is a beautiful young woman whose birth was foretold to bring great tragedy and conflict to the court of King Conor mac Nessa. The story of Deirdre's life, love, and eventual exile has been an integral part of Irish mythology and literature for centuries.

The name Deirdre gained widespread popularity in Ireland during the Middle Ages and continued to be a common name throughout the centuries. Some notable historical figures who bore the name include:

1. Deirdre of the Sorrows (fl. 1st century AD), the tragic heroine of the Irish legend mentioned earlier.

2. Deirdre ingen Chathail (fl. 13th century), an Irish noblewoman and the wife of Domhnall Mor O'Brien, King of Thomond.

3. Deirdre Bruaid (fl. 12th century), an Irish poet and scholar known for her works in Early Modern Irish.

4. Deirdre Warin (c. 1530-1574), an English noblewoman and the wife of William Sheldon of Beoley.

5. Deirdre of the Glens (fl. 17th century), an Irish folk heroine and the subject of several ballads and poems.

While the name Deirdre has Celtic roots, it has also been embraced by various cultures and communities around the world, particularly in the English-speaking regions influenced by Irish heritage and culture. The name's enduring popularity can be attributed to its melodic sound, rich historical significance, and the captivating tales associated with its legendary bearers.