WordWeb Online

1. Any day on which school is in session
   "go to bed early because tomorrow is a school day"
    
2. The period of instruction in a school; the time period when school is in session
   "when the school day was done we would walk home together";
   - school, schooltime

Derived forms: school days

Type of: day, period, period of time, time period, time span

Encyclopedia: School day