What is "seine-saint-denis"

Seine-Saint-Denis is a French department located in the Île-de-France region. Locally, it is often referred to colloquially as quatre-vingt treize or neuf trois (i.e. "ninety-three" or "nine three"), after its official administrative number, 93.

The learned and rarely used demonym for the inhabitants is Séquano-Dionysiens; more common is Dionysiens.