De eve et de treve
Defined in 2 dictionaries — Ballentine's (1916), Black's (1910)
Ballentine's Law Dictionary
James A. Ballentine · 1916
From grandfather and remote ancestors.
Black's Law Dictionary
Henry Campbell Black, M.A. · 1910
A law French phrase, equivalent to the Latin de avo et de tritavo, descriptive of the ancestral rights of lords in their villeins. Literally, "from grandfather and from great-grandfather's great-grandfather." It occurs in the Year Books.