The Superessive case is a grammatical declension

Declension

In linguistics, declension is the inflection of nouns, pronouns, adjectives, and articles to indicate number , case , and gender...

 indicating location on top of, or on the surface of something. Its name comes from Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 supersum, superesse: to be over and above.

While most languages communicate this concept through the use of adposition

Adposition

Prepositions are a grammatically distinct class of words whose most central members characteristically express spatial relations or serve to mark various syntactic functions and semantic roles...

s, there are some, such as Hungarian

Hungarian language

Hungarian is a Uralic language, part of the Ugric group. With some 14 million speakers, it is one of the most widely spoken non-Indo-European languages in Europe....

 which make use of cases for this grammatical structure.

An example in Hungarian: a könyveken means "on the books", literally "the books-on".

In Finnish, superessive is a type of adverb

Adverb

An adverb is a part of speech that modifies verbs or any part of speech other than a noun . Adverbs can modify verbs, adjectives , clauses, sentences, and other adverbs....

. For example:

kaikkialla means "everywhere" (literally "everything-at")

täällä means "(at) here" (from tämä - "this", lit. "at this place")