An ancient Egyptian symbol of the god Osiris, in form a small pillar with a number of flat sections towards the top.
To develop the higher mind one must first lower himself to raise the serpent, or set up the Tet pillar of Osiris.1981, William Irwin Thompson, The Time Falling Bodies Take to Light: Mythology, Sexuality and the Origins of Culture, London: Rider/Hutchinson & Co., page 222:
Tets are 44-chromosome conversions from 22-chromosome diploids, created by elaborate means involving colchicine, a chemical found naturally in crocuses. Only a tet can pollinate a tet, but some tets can pollinate themselves.2017, Susan Brownmiller, “Daylily Dreams”, in My City Highrise Garden, New Brunswick, NJ: Rutgers University Press, →ISBN, page 84:
tet
noun
Etymology Clipping of tetrahedron or tetrahedral.
1
Engineering, Geometry, Mathematics, Natural sciences, Physical sciences, Sciences A tetrahedron; a tetrahedral finite element.
All the tetras in my tank (3 species - black neons, Pristellas, and red eyes) died within a 36 hour period. The corys and otos in the same tank are fine. There was no change in water quality, feeding habits, or water temperature. I have no idea why all the tets would die in such a short time span.1998 January 24, LASP, “Dead tetras”, in rec.aquaria.freshwater.misc (Usenet):