Case:  

The distinctive form or position of a noun or pronoun that identifies its grammatical function. In Greek the case of a word is indicated more by its inflected form than its position, but at times its position will be a key factor in determining the case. Some grammars use case and function synonymously for the grammatical function of a word, and speak more narrowly of case endings. Others equate case and case_ending as denoting the form of the word, and distinguish that from grammatical function.