One day of sidereal time; the time in which Earth rotates once around its axis, relative to the point of the vernal equinox (about 23 hours, 56 minutes, 4 seconds).
The rotational period of Earth; the time in which Earth rotates around its axis 360 degrees.
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.