D defs.my
Entry 2 senses Webster, 1913

Eigne

· IPA /eɪn/
01 a. Eldest; firstborn.
  1. 1.
    Eldest; firstborn.(Law)
  2. 2.
    Entailed; belonging to the eldest son.[Obs.]
Phrases & compounds
Bastard eigne — a bastard eldest son whose parents afterwards intermarry.