These two in turn produce another pair, Geb and Nut.Finally, Geb and Nut, the earth and the sky, combine and produce the two pairs of Isis and Osiris, and Seth and Nephthys.The river brings forth new life (Horus) in the form of vegetation.
Seth, thinking his semen is in Horus, although he has actually eaten it himself as salad dressing, appears with Horus before the judges who will determine who has primacy among the archetypal beings.Seth tells the judges to call to the semen so that it can respond telling where it is.Nephthys spends all of her time with Isis, being of assistance to her in various ways.Seth, likewise, spends all of his time with Osiris and then with Osiris's son Horus, but unlike Nephthys he spends his time causing all kinds of havoc.They do, and much to Seth's surprise, the semen responds from his own belly, not from Horus's.
Seth is disgraced and Horus assumes the role as prime archetypal being.
Isis exemplifies the reproductive female, Osiris the reproductive male, Seth the nonreproductive eunuch, and Nephthys the unmarried virgin .
This story of the origins of the archetypal beings recapitulates the cellular process of meiosis in sexual reproduction, in which chromosomes are doubled, then shuffled, then divided, then shuffled, and then divided again.
Therefore, one would not necessarily expect such a woman to be recognized as not female, or as a third gender, especially in a patriarchal culture where women's desires were not counted.
But one would expect there to be at least one word for the nonprocreative man.
For information see Wallis Budge's Gods of the Egyptians and Plutarch's treatise On Isis and Osiris.