What is a cell type?
I do not know. We do not know.
This wikibase is a shot at formalizing meanings for cell types and cell type descriptors.
Properties characterize a given class. There might be specific properties for definition. Or qualifiers to tag caracteristics that are necessary and sufficient to describe any given cell type.
The initial idea is that every cell classification is a cell type. Implementation challenges will help to solve differences and so on.