Lat in the civil law. A great-great-grandmother's brother, (abaviae /rater.) Inst 3, 6, 6; Dig. 38, 10, 3. Called avunculus maximus. Id. 38,10,10, 17. Call-ed by Bracton and Fleta abavunculus magnus. Bract fol. 68b; Fleta, lib. 6, C. 2,119
Source: Black's Law Dictionary 2nd Ed (1910)