In geometry, the pentagonal orthobirotunda is one of the Johnson solids (J_34). It can be constructed by joining two pentagonal rotundae (J_6) along their decagonal faces, matching like faces. The pentagonal orthobirotunda is also related to an Archimedean solid, the icosidodecahedron, which can also be called a pentagonal gyrobirotunda, similarly created by two pentagonal rotunda but with a 36-degree rotation.