Case---a particular form of a nominal, pronominal or modifier that expresses a syntactical relationship between other morpho-phonic forms found in a sentence.
Adjective---a part of speech that modifies a substantive by means of suffixes such as -er and -est or by functioning syntactically in a predicative or attributive way.
Declension---a class of words belonging to one language with the same or a similar system of inflections.
Gender---a grammatical category used to classify nouns, pronouns, adjectives and sometimes verbs. Grammatical gender is not necessarily associated with actual gender.