The American Heritage® Dictionary of the English Language, 4th Edition
n. Any of various cagelike, hollow molecules composed of hexagonal and pentagonal groups of atoms, and especially those formed from carbon, that constitute the third form of carbon after diamond and graphite.
n. any of a class of allotropes of carbon having hollow molecules whose atoms lie at the vertices of a polyhedron having 12 pentagonal and 2 or more hexagonal faces
n. any closed-cage compound having twenty or more carbon atoms consisting entirely of 3-coordinate carbon atoms
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a form of carbon having a large molecule consisting of an empty cage of sixty or more carbon atoms
Word Usage
"The world known as Virga is a fullerene balloon 3,000 kilometers in diameter, filled with air, water, and aimlessly floating chunks of rock."