(1) “Agreement” means the federal-state agreement between the federal agency and the state of Tennessee entered into on August 16, 1951, as authorized by the Social Security Enabling Act for the purpose of extending coverage under Title II of the Social Security Act (42 U.S.C. §§ 401-425).

(2) “Commissioner of social security” includes any individual to whom the commissioner of social security has delegated any of the commissioner's functions under the Social Security Act (42 U.S.C. § 301 et seq.), with respect to coverage under such act of employees of states and their political subdivisions;

(3) “Employee” includes an officer of a state or political subdivision thereof;

(4) “Employment” means any service performed by an employee in the employ of the state, or any political subdivision thereof, for such employer, except:

(A) Service which, in the absence of an agreement entered into under this chapter, would constitute “employment” as defined in the Social Security Act; or

(B) Service which under the Social Security Act may not be included in an agreement between the state and the commissioner of social security, entered into under this chapter;

(5) “Employer” means the state, a political subdivision, or a local instrumentality of either;

(6) “Federal Insurance Contributions Act” means chapter 21 of the federal Internal Revenue Code of 1954 (26 U.S.C. § 3101 et seq.), as such code has been and may from time to time be amended or codified;

(7) “Modification” means an amendment to the original federal-state agreement to modify coverage for coverage groups or to extend coverage to additional coverage groups consistent with Section 218 of the Social Security Act (42 USC § 418) and this chapter;

(8) “Plan of agreement” means an agreement between the state social security administrator and an employer for the purpose of extending the benefits of the Social Security Act to coverage groups within its employ;

(9) “Political subdivision” includes an instrumentality of a state, or one (1) or more of its political subdivisions, including the Tennessee Municipal League, the Tennessee School Boards Association and the Tennessee County Services Association, or of a state and one (1) or more of its political subdivisions, but only if such instrumentality is a juristic entity which is legally separate and distinct from the state or subdivision and only if its employees are not by virtue of their relation to such juristic entity employees of the state or subdivision;

(10) “Social Security Act” means the act of congress approved August 14, 1935, chapter 531, 49 Stat. 620, officially cited as the “Social Security Act”, including regulations and requirements issued pursuant thereto, as such act has been and may from time to time be amended;

(11) “State agency” means the state old age and survivors insurance agency; and

(12) “Wages” means all remuneration for employment, regardless of the medium in which paid, which would constitute wages within the meaning of the Social Security Act, as amended.