As used in this subchapter, unless the context otherwise requires:
1. “Child” means any person under eighteen years of age.
2. “Governmental unit” means the state, or any county, municipality, or other political subdivision of the state, or any department, board, division, or other agency of any of these entities; an authorized representative of the state, or any county, municipality, or other political subdivision of the state, or of a department, board, division, or other agency of any of these entities; or a school district or an authorized representative of a school district.