tesseract

1. (mathematics, geometry) The four-dimensional analogue of a cube; a 4D polytope bounded by eight cubes (analogously to the way a cube is bounded by six squares).Examples: "Hence the cube determined by these axes is the face of the tesseract which we now have before us."; "[…]then it would trace out a higher cube, or tesseract, and each of the six surrounding cubes, carried on in the same motion, would trace tesseracts also,[…]."Synonyms: four-dimensional hypercube, 4-cube, 8-cell, octachoron, tetracube

2. (science fiction) Any of various fictional mechanisms that explain extradimensional, superluminal, or time travel outside the geometry of the physical universe.Examples: ""I shall just sit down for a moment and pop on my boots and then I'll be on my way. Speaking of ways, pet, by the way, there is such a thing as a tesseract.""; "When the Tesseract's energy levels spiked, Selvig proved unable to stop it and Loki arrived on Earth via a Tesseract-created portal."; "Cooper sees his younger self due to the tesseract in Interstellar."