These researchers contend that it is only after the fall of the Roman Empire and the Germanic invasions that the area of Neuilly was deforested and settled. Thus, they think that the name "Lulliacum" or "Lugniacum" comes from the ancient Germanic word "lund" meaning "forest", akin to Old Norse "lundr" meaning "grove", to which the placename suffix "-acum" was added. The Old Norse word "lundr" has indeed left many placenames across Europe, such as the city of Lund in Sweden, the Forest of the Londe in Normandy, or the many English placenames containing "lound", "lownde", or "lund" in their name, or ending in "-land." This interesting theory, however, fails to explain why the "d" of "lund" is missing in "Lulliacum" or "Lugniacum".