A terminus is an object used by a Shade to eliminate ghosts on contact. Ghosts that touch an activated device vanish and do not return; it is unknown if they succeed in 'moving on' or if they simply cease to exist. A terminated ghost often leaves a residual sweet, burning smell.
In The Name of the Star, Rory's roommate Boo uses a terminus in the guise of an out-dated mobile phone. She explains that because the old model had raised buttons, she is better able to use her terminus at a moment's notice by feeling for the correct buttons on the key pad without looking.
The copycat killer, Alexander Newman, wanted to investigate how and why a particular person becomes a ghost. During a forced experiment, Rory was made to hold a terminus in her hand as she slowly began to bleed out. She survived the attack, so it is unknown whether Rory would have successfully returned as a ghost. However, the incident left Rory with the power to destroy ghosts on contact with her skin, just like a terminus. This is an ability that the Shades had never before encountered.
In The Madness Underneath, the Shades' terminus supply has been diminished by Newman. However, Rory has absorbed the ability of the device to destroy ghosts on contact. Because of this, the Shades have to rely solely on Rory to terminate unruly ghosts.
Human Terminus Edit
Rory is unsettled by her new found 'terminus' ability, and it often makes her nauseous. She feels her fingers being drawn toward ghosts' bodies by an inexorable force like "the suction end of a vacuum". When this happens, a ripple of energy goes up Rory's arm, linking her to the ghost at her fingertips. After a rush of air, Rory sees a quick flash of light before the ghosts vanish and leave behind an "unsettling floral smell".
Rory becomes concerned about her lack of control, particularly when she comes close to terminating her friend Alistair by accident.