Deputy Human Resource Director

[mdickman@nsf.gov]

Is there a term for classifying types of nouns according to voice, singular or plural, or gender?

[Marylin]

Is there a term for classifying types of nouns according to voice, singular or plural, or gender?

I would say Deputy Director of Human Resources.
or
Deputy Director, Human Resources (mail address)

I am not sure I understand your question.

[Mister Micawber]

Many nouns inflect, at least for number,and the set of inflections is called a declension:

waiter
waiters
waitress

etc.