A Sime who Kills.

The condition of being 'joined to the Kill'

This is considered the normal state for Simes leading up to Unity, and those who do not Kill, the Nonjuncts and Disjunct, are considered 'freaks and unnatural'

After Digen's time (after 232 Unity ) medical science gradually reveals a much more nuanced understanding of the "junct" condition that has nothing to do with causing Gens to die and much to do with the Endowment