Usually treated as a variant of Aidan, the Irish name meaning "little fire," though it also resembles Persian Aydin forms.
Aidin is a variant of Aidan, itself derived from the Old Irish Aodhán — a diminutive of Aodh, the ancient Celtic god of the sun and fire. The name means 'little fire' in its original construction, a tender diminutive applied to a deity of immense elemental power. Aodh was one of the most venerated figures in pre-Christian Irish belief, and the name Aodhán was given to some of the early church's most significant figures as Christianity absorbed and transformed the older tradition.
The most historically towering bearer is Saint Aidan of Lindisfarne (died 651), the Irish monk who evangelized Northumbria and founded the monastery on the tidal island of Lindisfarne, known ever since as Holy Island. Bede, writing in the eighth century, described him as a man of extraordinary gentleness, generosity to the poor, and courage before the powerful — a saint who walked rather than rode, the better to speak with ordinary people along the road. The spelling Aidin emerged as the name crossed linguistic borders — into Persian, Turkish, and Central Asian contexts, where Aydın is an entirely separate name meaning 'enlightened' or 'bright' in Turkish, creating a remarkable coincidence of meaning across unrelated traditions.
In contemporary Western naming, Aidin offers the cultural weight of Aidan with a slightly more individuated appearance. It has been popular in Ireland, the United States, and Iran simultaneously — a name whose warmth transcends its many origins.