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.

Source: Webster's Revised Unabridged Dictionary (1913)