Flexitime

Flexitime is short for 'flexible work hours'. It allows workers some discretion over when they arrive at work and when they leave.

Workers have to work a specific number of hours per week, but they are free to vary the hours of work within certain limits.
Each day consists of a common core, usually six hours, with a flexibility band surrounding the core.
All workers are required to be at their jobs during common core period, but they are allowed to accumulate their other two hours before and/or after the core time.
Some flexitime programs allow extra hours to be accumulated and turned into a free day off each month.