Nerthus

Latinized form of Nerþuz, the Germanic (feminine) equivalent of Njörðr (see NJORD). Nerthus was a Germanic goddess of fertility as described by the Roman historian Tacitus in the 1st century.

NJORD   male   Norse Mythology, Swedish, Norwegian, Danish
From Old Norse Njörðr, which was possibly derived from the Indo-European root *ner meaning "strong, vigourous". Njord was the Norse god of the sea, sailing, fishing and fertility. With his children Freyr and Freya he was a member of the Vanir.
EQUIVALENTS
GERMAN: Herta, Hertha
MASCULINE FORMS
DANISH: Njord
NORSE MYTHOLOGY: Njord, Njörðr
NORWEGIAN: Njord
SWEDISH: Njord