icosahedral

This term is primarily used in technical, scientific contexts, particularly in virology and crystallography. It describes a specific geometric arrangement where twenty equilateral triangular faces meet, creating a highly stable structure. In biology, it is the standard descriptor for the protein shell of many viruses, such as the adenovirus.

Because it is a specialized geometric descriptor, it is almost exclusively used as an adjective to modify nouns like symmetry, capsid, or structure. It does not have a casual or metaphorical application in general English conversation.