Boranis III was the inhabited third planet in its system.

At some point, thousands of the inhabitants of the planet started dying from a plague without anyone knowing why. Fortunately, in 2372 Doctor Julian Bashir and an away team from Deep Space 9 were able to identify the pathogen within the hour and started to inoculate the water table. It took just three days to do so. (DS9: "The Quickening")

This planet was only mentioned in dialogue.
"bore-ON-us" was the pronunciation for this planet's name from the script pronunciation guide. [1]
In 2375, Bashir confused Boranis III with the Teplan homeworld when asked about the Quickening by Koval. (DS9: "Inter Arma Enim Silent Leges") It is possible that the Dominion was also involved in the situation on Boranis III, though after his initial failing on the Teplan homeworld, Bashir claimed that the plague was incurable because the Dominion knew what they were doing.
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