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Dictionary of Medieval Names
from European Sources

Frederica f. Fem. of Frederick.

Withycombe s.n. Frederica says that this name wasn't used in England until the 19th C, but this is not the case.

England
Early Modern English
1543 Frederick StAnthonlin p. 4
Cite as: S.L. Uckelman. "Frederica". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2016, no. 1. http://dmnes.org/2016/1/name/Frederica.