The Collaborative International Dictionary
Bastard eigne
Eigne \Eigne\, a. [OF. aisn['e], ainsn['e], F. a[^i]n['e], fr. L. ante natus born before. Cf. Esnecy.]
(Law) Eldest; firstborn.
--Blackstone.-
Entailed; belonging to the eldest son. [Obs.]
Bastard eigne, a bastard eldest son whose parents afterwards intermarry.
Wiktionary
bastard eigne
n. A bastard eldest son whose parents afterwards intermarry.