"Secondary" was a title applied to individuals in the Outbound Flight Project who were weakly sensitive to the Force. Secondaries' Force-sensitivity was considered too weak for them to become Jedi, but strong enough to create Jedi offspring.
Secondaries were Force-sensitive individuals in the Outbound Flight Project. Jedi Master Jorus C'baoth, the project's leader, believed secondaries' Force-sensitivity was too weak to become Jedi. However, he selected families for the project with secondary members, as secondaries were the most likely to produce children Forceful enough for Jedi training.
Shortly after the Outbound Flights launch in 27 BBY, Master C'baoth arranged a reception on Dreadnaught-Four for children aged four to ten years old intended for Jedi training, as well as those children's families. The Outbound Flight Project aimed to colonize extra-galactic space, and to discover Force-sensitive species beyond the borders of the Galactic Republic from whom new Jedi could be trained. Because of the Project's goals, and because secondaries were likely to have Jedi children, Jedi Master Justyn Ma'Ning and Jedi Knight Lorana Jinzler invited secondaries and their families to the reception as well, much to C'baoth's chagrin. Ma'Ning and Jinzler, C'baoth's former Padawan, wanted to prepare the secondaries for the likely event that their families may produce Jedi descendants in the future, but C'baoth preferred to deal with that possibility if and when it happened.
Dillian Pressor was a secondary, and his son Jorad Pressor wished to become a Jedi.
Secondaries appeared in Timothy Zahn's 2006 novel Outbound Flight.