Full Idea
An 'atomless gunk' is defined to be an individual possessing no parts that are atoms.
Gist of Idea
'Gunk' is an individual possessing no parts that are atoms
Source
Charles Chihara (A Structural Account of Mathematics [2004], App A)
Book Reference
Chihara,Charles: 'A Structural Account of Mathematics' [OUP 2004], p.352
A Reaction
[Lewis coined it] If you ask what are a-toms made of and what are ideas made of, the only answer we can offer is that the a-toms are made of gunk, and the ideas aren't made of anything, which is still bad news for the existence of ideas.