For purposes of sections 79-824 to 79-842, unless the context otherwise requires:
(1) Certificated employee means and includes all teachers and administrators as defined in section 79-101, other than substitute teachers, who are employed one-half time or more by any class of school district;
(2) School board means the governing board or body of any class of school district;
(3) Probationary certificated employee means a teacher or administrator who has served under a contract with the school district for less than three successive school years in any school district, unless extended one or two years by a majority vote of the board in a Class IV or V school district, except that after September 1, 1983, in Class IV and V school districts the requirement shall be three successive school years. Probationary certificated employee also means superintendents, regardless of length of service;
(4) Just cause means: (a) Incompetency, which includes, but is not limited to, demonstrated deficiencies or shortcomings in knowledge of subject matter or teaching or administrative skills; (b) neglect of duty; (c) unprofessional conduct; (d) insubordination; (e) immorality; (f) physical or mental incapacity; (g) failure to give evidence of professional growth as required in section 79-830; or (h) other conduct which interferes substantially with the continued performance of duties;
(5) Permanent certificated employee means a teacher or administrator who has served the probation period as defined in this section; and
(6) School year, for purposes of employment, means three-fourths of the school year or more on duty, exclusive of summer school.
A certificated employee who has been hired to fulfill the duties of another certificated employee who is on leave of absence shall not accrue rights under sections 79-824 to 79-842 during the period that the employee is fulfilling such duties.