a solid figure having 20 faces. The faces of a regular icosahedron are equilateral triangles.

What is meant by icosahedral?

: a polyhedron having 20 faces.

What is icosahedral symmetry of virus?

The capsid has 6 5-fold rotation axes, 10 3-fold axes, and 15 2-fold axes, the symmetry elements of an icosahedron. The subunits can be divided into 12 capsomers that contain five subunits (pentamers) and 20 capsomers that contain six subunits (hexamers). Icosahedral symmetry of a viral capsid.