Eigne \Eigne\, a. [OF. aisn['e], ainsn['e], F. a[^i]n['e], fr. L. ante natus born before. Cf. {Esnecy}.] 1. (Law) Eldest; firstborn. --Blackstone. 2. Entailed; belonging to the eldest son. [Obs.] {Bastard eigne}, a bastard eldest son whose parents afterwards intermarry.