Renegade Dwarf is a derogatory term used to describe someone who is half-Dwarf and half-human.
After the Telmarine Conquest (c.1995 NY), all sentient non-humans (Old Narnians) were massacred or forced into hiding by the Telmarines. Some Dwarfs, with the Talking Beasts and Fauns who survived, created hidden communities in the wood and continued to marry each other, preserving a pure Dwarf bloodline. Others, however, shaved their beards, wore high-heeled shoes, and lived with the Telmarines, pretending to be men and marrying humans. From these came a line of half-Dwarfs who lived among the Telmarines until the Narnian Revolution (c. 2300 NY).
- "I am... a half-Dwarf, and if any of my kindred, the true Dwarfs, are still alive anywhere in the world, doubtless they would despise me and call me a traitor. But never in all these years have we forgotten our own people and all the other happy creatures of Narnia, and the long-lost days of freedom."
- ―Doctor Cornelius[src]
Many of the full-blooded Dwarfs, especially Black Dwarfs, hated the half-Dwarfs even more than they hated the Telmarines. This hatred was unfounded; all known half-Dwarfs were loyal to their kindred and to Old Narnia. In fact, the half-Dwarf Doctor Cornelius was instrumental in the Narnian Revolution to take Narnia back from the Telmarines.