"Variant of Margaret"
The name Margaretha is commonly a female name from the "Greek" origin.
Margaretha is the German and Dutch form of Margaret, the same name as Latin Margarita and Greek margarites. The Greek word margarites means pearl, and the name entered western European languages through Latin. German, Dutch and Scandinavian usage favours forms such as Margaretha, Margarete and Margareta, while English uses Margaret.
Margaret means "A combination of Elly and May, Old soul and great, pink / white blossom or born in the month of May.".
The pronunciation of Margaretha is mar-guh-REE-thuh.