Of a child: born after the father's death, or after the execution of the father's will. Also (Roman Law): born after the composition of the father's last will.
2Born later; born after another person, especially a sibling; younger.
Now usually in form afterborn. An after-born person or child. Also (with plural agreement, usually with the): after-born people or children considered collectively. Now chiefly Law.
Old English; earliest use found in The Aldhelm Glosses. From after- + born.