(Also Tefnet, Tefenet, Greek Tphenis)
”Tongue of Ptah”
“Sky-spittle”
“Lunar Eye of Ra”
“She Of Moisture”
“Lady of the Flame”
“Uraeus on the Head of all the Gods”
"Atem is he who masturbated in Iunu. He took his phallus in his grasp that he might create orgasm by means of it, and so were born the twins Shu and Tefnut."
-- Pyramid Text 1248-49
Tefnut is a primeval Egyptian water goddess (one of the Ennead). A twin and wife of Shu, and a creation of the self-created god Atem (a form of Ra), she was the mother of Geb (earth) and Nut (sky). She was a protector of Osiris and sometimes considered the left eye of Horus. The name Tefnut contains the root 'Tef', which relates to moisture or spit, and 'Nu' meaning sky or waters.
She was the lunar goddess of moisture and humidity, in particular dew, mist, clouds and rain. She was also a solar goddess, associated with the sun-god, and dryness (the absense of moisture). Her tears when they fell to the ground became incense-bearing plants and, in the pyramid texts, she was said to create pure water from her vagina. Her principal sanctuary was at Heliopolis.
Like many water dieties, she was seen as a goddess of creation. In her role as the 'Tongue of Ptah', she aided Ptah in his creations by carrying out his will (Mennefer). Tefnut was also considered a female form of Shu, her husband-brother), wherein her main tasks would have been beginning the creation cycle and birthing Shu’s children (Lunu and Thebes).
Tefnut is generaly depicted as a woman with a lion’s head, with a solar disk and uraeus, and seated on a throne. She may also be shown holding a sceptre and an ankh. In this aspect, she resembles Sekhmet, but Sekhmet’s ears are rounded, while Tefnut’s are pointed. Less often, she is shown as a full lioness, with her brother Shu (at Leontopolis). Very rarely, Tefnut was depicted as a full woman, or a snake coiled around a sceptre. In the New Kingdom, she, as the mother of Nut, was depicted in art as a female sphinx trampling the enemies of the Two Lands.
This goddess appears in a number of legends. In one story, she and her brother Shu go off to explore the waters of Nun. Ra, believing they were lost, sent out his Eye into the Chaos. When he found them, he was so happy that he wept, and his tears which fell to earth became the first humans. In another, an upset Tefnut fled from her father to Nubia, taking all of the moisture with her. While draught raged in Egypt, she changed herself into a lioness and went on a killing spree in her anger at her father. Ra, deciding he missed her, sent Thoth and Shu to find her and bring her back to Egypt. In the end, she was escorted back to Egypt with a host of Nubian followers, and went from city to city restoring the water (the inundation).
Sources:
http://www3.sympatico.ca/untangle/egyptian.html
http://www.kemet.org/glossary/tefnut.html
http://www.thekeep.org/~kunoichi/kunoichi/themestream/tefnut.html