Fjorgynn (pronounced roughly “FIOR-gen” with a hard “g”) and Fjorgyn (pronounced roughly the same) are a divine pair in Norse mythology. Fjorgynn (Old Norse Fjörgynn) is male and Fjorgyn (Old Norse Fjörgyn) is female.
References to either of these giants and/or deities in Old Norse literature are few and far between. They play no active part in the surviving mythological tales. Therefore, everything that we know about them has to be cobbled together from passing references and the study of comparative religion.
Fjorgyn is sometimes said to be the mother of Thor. Elsewhere, Thor’s mother is said to be the equally elusive Jord. Since “Jord” (Old Norse Jörð) is the Old Norse word for “Earth,” and since fjörgyn (as a common noun with a lowercase “f”) is commonly used in Old Norse poetry to signify “earth” in a general sense, Jord and Fjorgyn seem to be identical or at least closely related.
While the etymology (linguistic origin) of the words “Fjorgyn” and “Fjorgynn” is unknown, many scholars have proposed that the former could be related to Old English fruh, Old High German furuh, and Latin porca, all of which mean “furrow” or “ridge.” This in turn suggests a connection to an Old English prayer to an Erce, eorþan modor (“Erce, mother of earth”), which was recited when the plow cut the first furrow of the growing season, and milk, honey, flour, and water were poured into the soil. All of this indicates that Fjorgyn was extension of the “earth mother goddess” type that was so prevalent throughout the ancient Germanic (and wider Indo-European) world.
And what about the male Fjorgynn?
References to him in Old Norse literature are even sparser than those to his female counterpart. In the Lokasenna, one of the poems in the Poetic Edda, the goddess Frigg is called Fjörgyns mær. This phrase can be literally translated as “Fjorgynn’s maiden,” which could mean either “Fjorgynn’s daughter” or “Fjorgynn’s mistress.” The medieval Icelandic historian Snorri Sturluson claimed that Frigg was Fjorgynn’s daughter, but Snorri can’t be taken at face value. The passage in the Lokasenna has Loki taunting Frigg over her infidelity and promiscuity, and in that context, mær can hardly mean anything but “mistress.”
So this passage tells us nothing about Fjorgynn except that he slept with Frigg. Of course, few if any of the Norse gods and goddesses have been noted for their chastity or fidelity, so this passage tells us essentially nothing about Fjorgynn.
Unfortunately, those two throwaway mentions are Fjorgynn’s only appearances in Old Norse literature. To gain any insight into Fjorgynn’s character, then, we have to turn to another kind of source: comparative religion.
The thunder god of the Slavs and Balts of Eastern Europe, who was called Perun (“Striker”) or Perkunas, was essentially identical to Thor in his attributes and role within the Slavic and Baltic pantheons and mythologies. There are also many areas of overlap between those deities and the Hindu storm god Parjanya. Such correspondences are relatively common amongst the various branches of the Indo-European peoples, which include the ancient Slavs, Balts, Norse, and Indians (India’s Indians, not American Indians, of course).
This makes it all the more intriguing that the names “Fjorgynn,” “Perkunas,” and “Parjanya” all seem to derive from the same Proto-Indo-European word. If you reverse the sound shifts that eventually differentiated the Germanic, Baltic, and Sanskrit languages from the Proto-Indo-European language thousands of years ago, you end up with something like *Perkwunos. In the Proto-Indo-European religion, *Perkwunos was likely a prominent god of the sky, storm, and rain. Since the Proto-Indo-European language and religion are unattested, there are no written documents that could explicitly confirm this, but the functional and linguistic similarities here are simply too close to be coincidences.
If Fjörgynn corresponds to the Lithuanian Perkunas/Slavic Perun/Indian Parjanya, and if Fjörgyn means “earth,” then Fjorgynn and Fjorgyn would be a pair that corresponds exactly to Thor and his wife Sif and to the wider Indo-European hieros gamos or divine marriage between a sky god and an earth goddess. Thus, Fjorgynn and Thor are effectively identical, as are Fjorgyn, Jord, and Sif. Here we have a replication of a deep-seated concept rather than a set of storybook-like discrete deities. It’s by no means straightforwardly clear how this constellation of related conceptions gave rise to the almost identical names Fjorgynn and Fjorgyn, but it seems likely that this feature, too, goes back to the Proto-Indo-European period, given the similarity of the Norse fjörgyn and Latin porca.