In geometry, a **demihepteract** or **7-demicube** is a uniform 7-polytope, constructed from the 7-hypercube (hepteract) with alternated vertices truncated. It is part of a dimensionally infinite family of uniform polytopes called demihypercubes.

E. L. Elte identified it in 1912 as a semiregular polytope, labeling it as HM_{7} for a 7-dimensional *half measure* polytope.

Coxeter named this polytope as **1**_{41} from its Coxeter diagram, with a ring on one of the 1-length branches, and Schläfli symbol
{
3
3
,
3
,
3
,
3
3
}
or {3,3^{4,1}}.

Cartesian coordinates for the vertices of a demihepteract centered at the origin are alternate halves of the hepteract:

(±1,±1,±1,±1,±1,±1,±1)

with an odd number of plus signs.

There are 95 uniform polytopes with D_{6} symmetry, 63 are shared by the B_{6} symmetry, and 32 are unique: