"Variant of Łucja"
The name Lusia is commonly a female name from the "Polish" origin.
Lusia is a Polish diminutive of Łucja, the Polish form of Lucia, formed with the common Polish ending -sia, as in Kasia from Katarzyna and Basia from Barbara. It is used as a given name in its own right, not only as a household pet form. Its appearance in United States birth records from 1916 is consistent with Polish immigration to the United States in that period.
The pronunciation of Lusia is LOO-shuh.