a “Nor” refers to a type of space station. Specifically, Nor-class space stations were used by the Cardassians, a species of humanoid aliens, during their occupation of Bajor. The Cardassians used these stations to maintain their control over Bajor and its people, and they were known for their harsh and oppressive conditions.
After the Cardassians withdrew from Bajor, the Bajoran government took control of the Nor-class stations and repurposed them for their own use. One such station, Terok Nor, was renamed Deep Space Nine and became the setting for the TV series of the same name.