Is the word staff a abstract noun?

Answer 1

No, the noun 'staff member' is a singular, common, compound, concrete noun; a word for a person.

A collective noun is a word used to group people or things taken together as one whole in a descriptive way, for example:

• a staff of employees (staff is the collective noun)
• a group of members (group is the collective noun)

Answer 2

The noun 'staff' is an abstract noun as a word for something that is a source of strength (bread is the staff of life).

The noun 'staff' is a concrete noun as a word for physical persons or a physical thing:

• a group of employees;
• military officers who assist a commanding officer in planning and management;
• a pole used to carry an insignia or flag;
• a long stick used for making walking easier;
• the five horizontal lines and the spaces on which music is written.