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 the days of a week on which work is done. The five workdays in many countries are usually Monday to Friday (and are defined as such in official and legal usage even though many people work on weekends).
That part of a day in which work is done.