The Collaborative International Dictionary
Postgeniture
Postgeniture \Post*gen"i*ture\ (?; 135), n. [Pref. post- + L.
genitura birth, geniture.]
The condition of being born after another in the same family;
-- distinguished from primogeniture. [R.]
--Sir T. Browne.
Wiktionary
postgeniture
n. The fact of being born after someone else of the same bloodline.