office hours vs working day

office hours

noun
  • The times, typically from about 9am to 5pm, Monday to Friday, when non-24/7 office workers are at their desks. 

  • A 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. 

working day

noun
  • Any of those days of a week on which work is done, officially Monday to Friday in many countries (even though many people work on weekends). 

  • The part of a day in which work is done; the number of hours one must work per day for a specified wage. 

How often have the words office hours and working day occurred in a corpus of books? (source: Google Ngram Viewer )