1.NounThe times, typically from about 9am to 5pm, Monday to Friday, when non-24/7 office workers are at their desks.
"To request a brochure, please call during office hours."
2.NounA pre-arranged time when a person whose occupation frequently takes them away from their office during working hours is available in their office to answer questions or provide assistance without the requirement for an appointment.
"If you need help with the homework, the professor will be holding office hours on Thursday from 7–9pm."