Great dodecahemidodecahedron
Type	Uniform star polyhedron
Elements	F = 18, E = 60 V = 30 (χ = −12)
Faces by sides	12{5/2}+6{10/3}
Coxeter diagram
Wythoff symbol	5/3 5/2 | 5/3 (double covering)
Symmetry group	Ih, [5,3], *532
Index references	U70, C86, W107
Dual polyhedron	Great dodecahemidodecacron
Vertex figure	5/2.10/3.5/3.10/3
Bowers acronym	Gidhid

In geometry, the great dodecahemidodecahedron is a nonconvex uniform polyhedron, indexed as U₇₀. It has 18 faces (12 pentagrams and 6 decagrams), 60 edges, and 30 vertices.^[1] Its vertex figure is a crossed quadrilateral.

Aside from the regular small stellated dodecahedron {⁵/₂,5} and great stellated dodecahedron {⁵/₂,3}, it is the only nonconvex uniform polyhedron whose faces are all non-convex regular polygons (star polygons), namely the star polygons {⁵/₂} and {¹⁰/₃}.

It is a hemipolyhedron with 6 decagrammic faces passing through the model center.