A very tiny WalledGarden. A clique of n pages (for some small n, but n should be at least 2), with a common theme or topic, and with copious links among themselves (or to external sites), but little or no links to other sites on Wiki. Frequently OffTopic as well.
(A single page with no links, or links to itself, is an OrphanPage, not a WalledFlowerpot.)
There must be algorithms to find these, does anyone know of one off-hand? See WikiLinkStructureAnalysis.