In this subchapter, "teacher" means a principal, supervisor, classroom teacher, school counselor, or other full-time professional employee who is required to hold a certificate issued under Subchapter B or a nurse. The term does not include a superintendent or a person who is not entitled to a probationary, continuing, or term contract under Section 21.002, an existing contract, or district policy.
Tex. Educ. Code § 21.101