What is "prismane"

n. (context organic compound English) a polycyclic hydrocarbon, C₆H₆, having the shape of a regular triangular prism; any derivative of this compound

Prismane is a polycyclic hydrocarbon with the formula CH. It is an isomer of benzene, specifically a valence isomer. Prismane is far less stable than benzene. The carbon (and hydrogen) atoms of the prismane molecule are arranged in the shape of a six-atom triangular prism—this compound is the parent and simplest member of the prismanes class of molecules. Albert Ladenburg proposed this structure for the compound now known as benzene. The compound was not synthesized until 1973.