Where does “Μαυρουσία” come from?

Μαυρουσία (Ancient Greek) comes from Ancient Greek Μαυρούσιος, from Ancient Greek -ούσιος, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

Ancestry of “Μαυρουσία”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Μαυρούσιος	an inhabitant of Mauretania; a Mauretanian
2	Ancient Greek	-ούσιος	forms relational adjectives: of or pertaining to
3	Ancient Greek	-ῐος	belonging to; of”, “belonging to”, “pertaining to
4	Proto-Indo-European	-yós	Creates adjectives from noun or verb stems

Words derived from “Μαυρουσία”

Maurūsia
Maurusia
Maurusia
Maurusie

Every word from Proto-Indo-European -yós →Every word from Ancient Greek -ῐος →Every word from Ancient Greek -ούσιος →