demonymy means the use or study of demonyms. Lexicurio rates it Sui generis — a strength score of 87 out of 100.
Etymology
From demo- + -onymy.
noun
- The use or study of demonyms.“In keeping with French standards of demonymy, the word oulipian is capitalized here only when it refers to a person: Georges Perec was an Oulipian, but his output was (for the most part) oulipian.”