Eigne
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
L. Fr. Eldest; eldest-born. The term is of common occurrence in the old books. Thus, bastard eigne means an illegitimate son whose parents afterwards marry and have a second son for lawful issue, the latter being called mulier puisne, (after-born.) Eigne is probably a corrupt form of the French "aini," 2 Bl. Comm. 248; Litt. § 399.