Respective case

The respective case is a term invented by Anthony Appleyard for a rather mysterious noun case created by J. R. R. Tolkien in his constructed language Quenya (the elven language of the book "The Lord of the Rings"); Tolkien himself never named the case (at least, not in any of his published writings). Since the exact function of this noun case is unclear, a more neutral term is the "s-case", since it is formed by appending an -s to the word it modifies. It is not clear if this case is used with prepositions, transitive or intransitive verbs, or has a more general use. Based on a few examples, Helge Fauskanger has deduced the possibility that it is used as a kind of locative (e.g.: "i coa i taures / i coa i tauressë" the house in the forest).
Another possible use is to translate expressions with the preposition “about.” For example, in translating “He told me about the invasion,” the Quenya word for “invasion” might appear in the respective/dedative. The seeming absence of any other case being used to translate this preposition lends support to this conjecture. Ales Bican wrote an article exploring these and other possible functions for the s-case.
In the constructed language Ithkuil the case corresponding to the preposition about is called referential case.