A rectangular prism.
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cuboid
A rectangular prism.
A hexahedron, or cube.
Hexahedron
A cuboid.
A pentagonal prism.
A cuboid.
A pentagonal prism
A rectangular prism is a hexahedron with some rectangular sides. There is no requirement that all sides be rectangles. If they are, the solid is a right rectangular prism, or cuboid.
The solid is a cuboid, or "right rectangular prism" in which all angles are right angles. It is a box shape, or regular hexahedron.