For a child without any parents, there is a term - orphan. Is there such a term for the opposite - an adult without any children?
This question actually comes out of a software development situation where I have nodes that relate to each other as parents and children - a parent node has zero or more children. If a child doesn't have a parent, it's refered to as an orphan node. I'm looking for a term for a node that doesn't have any children. I considered "childless", "non-parent" etc, but was wondering if there is a proper non-negative term similar to orphan?
Edit: I'm not specifically asking for a word for someone who once had children but now doesn't. While orphan implies not only that a child currently has no parents, but (as a consequence of how life works) also that the child used to have parents but lost them; the same is not necessarily true for the term I'm asking about - a term to describe people without children, regardless of whether they did once have children. Bottom line: it's not about having had but lost children but simply about not currently having children, period.