worknight

Noun

 * 1) A night during which work is done.
 * 2) An evening before a day one has to work; a school night for someone who works rather than goes to school; typically the evenings of Sunday to Thursday.

Usage notes
In sense "night before working day", typically indicates evenings of Sunday to Thursday, which is the prior range of days to coordinate term, namely Monday through Friday, and hence a potential source of confusion.