This paper intends to study the history of the Old Irish word aue "descendent, grandchild" in both qualitative and quantitative approach. The former approach tries to demonstrate what forms this word evolved into from the early Old Irish period up to the end of the Middle Irish period, and to establish the phonological changes it underwent in accordance with our present understanding of the history of the Irish language. The latter approach is based on a linguistically annotated corpus of the Annals of Ulster, and shows the distribution of the variant forms of aue in relation to the period they are attested in. The discrepancy between the two observations is discussed and various hypothesis are raised to explain it.