Wiktionary
cucurbitane
n. (context organic compound English) An isomer of lanostane.
Wikipedia
Cucurbitane
Cucurbitane is a chemical compound with formula ( CAS number 65441-59-0). It is a polycyclic hydrocarbon, specifically a triterpene. It is an isomer of lanostane (specifically 19(10→9β)abeo-lanostane), from which it differs by the formal shift of a methyl group ( carbon number 19) from the 10 to the 9β position in the standard steroid numbering scheme.
The name is applied to two stereoisomers, distinguished by the prefixes 5α- and 5β, which differ by the handedness of the bonds at a particular carbon atom (number 5 in the standard steroid numbering scheme).