This paper will examine the role and structure of adjectival epithets in Irish personal names. Adjectival epithets are qualifiers added to a personal name which indicate a particular quality or physical characteristic, e.g. Aodh Ballach ‘Freckled Hugh’ or Tomás Carrach ‘Rough-skinned Thomas’. A number of these epithets are attested from a very early date in Irish-language sources, and the frequency of these attestations increases significantly from the 12th century onwards, in both Irish manuscript sources and in sources associated with the English administration in Ireland during the Tudor period. These documents indicate naming practices among various social groups in Ireland during the medieval period and indeed, aspects of these practices are still in use today, primarily within Irish-speaking communities in Ireland. This paper will provide examples of these epithets, explore their possible function, and ask what these epithets might reveal about naming practices in Irish society during the late-medieval period.