1. Having the shape of two pyramids joined at their bases; consisting of two pyramidal forms united at a common base.
Usage: Commonly used in chemistry and crystallography to describe molecular geometry and crystal structures.

Examples

• The bipyramidal geometry of the PCl₅ molecule consists of three equatorial chlorine atoms and two axial ones.
• In crystallography, a bipyramidal crystal form displays two pyramids meeting at a common base.
• The trigonal bipyramidal shape is common in coordination chemistry.
• Sulfur hexafluoride does not adopt a bipyramidal structure; it is octahedral instead.
• The bipyramidal arrangement minimizes electron repulsion in certain molecular configurations.