In geometry, a demiocteract or 8-demicube is a uniform 8-polytope, constructed from the 8-hypercube, octeract, with alternated vertices removed.
It is part of a dimensionally infinite family of uniform polytopes called demihypercubes.
Coxeter named this polytope as 151 from its Coxeter diagram, with a ring on one of the 1-length branches, and Schläfli symbol
Cartesian coordinates for the vertices of an 8-demicube centered at the origin are alternate halves of the 8-cube: with an odd number of plus signs.
This polytope is the vertex figure for the uniform tessellation, 251 with Coxeter-Dynkin diagram: