he etymological study of Early Irish began in the Old Irish period (c. 700‒900 A.D.), under the influence of Isidore of Seville’s Etymologiae, and, because of its flexible hermeneutic potential,it enjoyed great popularity in the middle and early modern period. It is only with the rise of modern comparative linguistics, especially of Indo-European linguistics in the second half of the 19thcentury, that the art of Irish etymology has attained scholarly riguour. Over the past150 years, paradigm shifts in Indo-European studies (laryngeal theory, accent/ablaut classes of inflection, derivational morphology) and the development of modern technology (digitisation of texts, eDIL, ISOS) have repeatedly changed the methods and the course of Irish etymological studies. The impact of some of these external factors will be illustrated with examples.