Sui generis
A similar case that led to the use of the label "sui generis" is the relationship of New Caledonia relative to France, because the legal status of New Caledonia can aptly be said to lie somewhere between a French overseas collectivity and a sovereign nation. Although other examples of such status for other dependent or disputed territories may exist, this arrangement is unique within the French realm.
Boggart
Boggart is one of numerous related terms used in English folklore for either a household spirit or a malevolent "genius loci" inhabiting fields, marshes or other topographical features. Other names of this group include "bug", "bugbear", "bogey", "bogun", "bogeyman", "bogle", etc., presumably all derived from (or related to) Old English "pūcel", Irish púca and Welsh "bwg" with the same meaning (itself a probable loan from the English "bug").