a four- dimensional hypercube

a four-dimensional object

a fourth dimensional geometric shape, which is represented in three dimensional space and time as a 'hypercube'

a name sometimes used for the extension of a cube to four-dimensions

an example of afour-dimensional object

a three-dimensional object

In geometry, the tesseract, also called 8-cell or octachoron, is the four-dimensional analog of the (three-dimensional) cube, where motion along the fourth dimension is often a representation for bounded transformations of the cube through time. The tesseract is to the cube as the cube is to the square; or, more formally, the tesseract can be described as a regular convex 4-polytope whose boundary consists of eight cubical cells.