In this article, unless the context otherwise requires:
1. "Classification" means the names of the positions, and the ranks and classes thereof, in the police and fire departments and peace officers' units subject to this article.
2. "Month" means thirty days.
3. "Peace officers" include regularly salaried deputy sheriffs, policemen and police officers of duly organized police departments.
4. "Professional firefighter" means a member of an organized and paid fire department.