For the passage cited from BT Ket 85a(47) see, for a quite different and rather convincing interpretation as a gentilic, A. Demsky, "Abbaye’s Family Origins:
A Study in Rabbinic Genealogy”, in Z. Weiss et al. eds, “Follow the Wise”
Studies in Jewish History and Culture
in Honor of Lee I. Levine (Eisenbrauns, 2010) pp. 235ff.