As used in this section:
(a) The term "agency" means all state departments, agencies, authorities, quasi-public corporations and all political subdivisions, including cities, counties, boards of education and public service districts, except, for the purposes of this section, the term "agency" does not include the state institutions of higher education known as Marshall University and West Virginia University.
(b) The term "architectural and engineering services" includes those professional services of an architectural or engineering nature as well as incidental services that members of those professions and those in their employ may logically or justifiably perform.
(c) The term "director of purchasing" means any individual assigned by any agency to procure the services of architects and engineers.
(d) The term "firm" or "professional firm" means any individual, firm, partnership, corporation, association or other legal entity permitted by law to practice the professions of architecture and engineering.