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.
Issue (genealogy)
"Issue" typically means a person's lineal descendants—all genetic descendants of a person, regardless of degree. Issue is a narrower category than heirs, which includes spouses, ancestors, and collaterals (siblings, cousins, aunts, and uncles). This meaning of issue arises most often in wills and trusts. A person who has no living lineal descendants is said to have died without issue.