Finding concepts that are similar to a given concept can prove useful in constructing user-friendly interfaces for querying DL-ontologies - the concrete use case being a query answering system with an enhanced user interface that suggests semantically relevant keywords (based on concept similarity) during query formulation. Most investigations on the similarity of concepts rely on ad-hoc and non-robust constructions referring to syntactical relationships in the concept hierarchy. A more promising approach to concept similarity is first to ground the concepts in a topological, geometrical, or more generally a spatial semantics and then to use the corresponding proximity or nearness relations provided by the spatial semantics for deciding concept similarity. Such an approach would not only describe a semantical justification for similarity of concepts but also provide a more cognitive semantics in the style of Gärdenfors conceptual spaces that advance the comprehension by non-professional users of DL-systems. This paper discusses some possible directions for a spatially oriented semantics for DLs, starting off from conceptual spaces and the region connection calculus.
