Declán is the Old Irish form of the name Declan, a name of uncertain etymology. This historical spelling is preserved in the records of the early Irish saint Declán of Ardmore, whose name in Old Irish was Declán mac Eircc. In modern Irish, the equivalent form is Deaglán or Deuglán. Etymology and History The root modern name Declan is an Anglicized form of Irish Deaglán, which itself derives from the Old Irish Declán. The meaning of the name is unknown, despite various speculative etymologies. Saint Declán (Old Irish: Declán mac Eircc) was a 5th-century missionary who converted the Déisi Muman, a people of Munster, and founded the monastery at Ardmore (Ard Mór) in present-day County Waterford. According to the 12th-century Latin Vita of Saint Declán, he is presented as a pre-Patrician saint, meaning that he brought Christianity to Ireland before Saint Patrick. He is considered a patron saint of the Déisi of East Munster, alongside such figures as Saint Ailbe of Emly and Saint Ciarán of Saigir. Notable Bearers Beyond the early saint, the name Declan has been borne by various historical and modern figures. The name gained contemporary popularity in English-speaking countries, notably in the United States, where it saw increased usage after the release of the movie The Jackal (1997) and particularly the romantic comedy Leap Year (2010), which features an Irish character named Declan. Meaning: Unknown; possibly pre-Irish origin Origin: Old Irish Type: First name Usage regions: Ireland, English-speaking countries Related forms: Declan, Deaglán