Noun
adposition (plural adpositions)
(grammar) An element that combines syntactically with a phrase and indicates how that phrase should be interpreted in the surrounding context; a preposition or postposition.
In addition, there is a "relator" (which can be of multiple lexical categories, but is most commonly an affix or adposition). Source: Internet
The essive case is marked by use of the adposition "en", which translates to English as "on". Source: Internet