Lutetia Parisiorum (mud or river-dwellings of the Parisii) was the Roman name of the city of Paris and the first it's mentioned by. It may be a corruption of a Celtic name given to it in the middle of the third century BCE by its founders, the Celtic tribe known to the Romans as Parisii but the older name has been lost in time so it may just as well be an original Roman name.
In later years, the official Roman naming of Civitas Parisiorum, given after the Roman conquest in 52 BCE, evolved into the city's current name. The use of Paris as an abbreviation of its official name took over from Lutetia and became predominant around the fourth century CE. Most of Lutetia was actually not the original fortified settlement on the Île de la Cité which was burned down by the inhabitants when responding to Vercingetorix' call to arms against the Romans but a Roman-built town on the left bank of the Seine built after the conquest.
While it may be known and mentioned in many academic texts, the name Lutetia also became a feature of contemporary culture through the Asterix comic book series which is set during the Roman occupation of Gaul.