Oblique case

Oblique case is a non-canonical case which is assigned by a governing preposition. See Of-insertion and inherent case.

In older work in Western linguistics, especially in the grammar of Indo-European languages, the term oblique case refers to all cases other than the nominative and the vocative (these are also called direct cases).

Origin
This use of the term goes back to antiquity (Latin obliquus, itself based on a semantic loan from Greek).

Links
Utrecht Lexicon of Linguistics

Other languages
German obliquer Kasus