[Latin, For the time being.] An abbreviation used for pro tempore, Latin for "temporary or provisional."
A person who acts as a temporary substitute serves pro tem. The term is often used to describe the acting head of a governing body, such as the president pro tem of the Senate, who presides over the Senate when the vice president is unable to do so.
Law Library - American Law and Legal InformationFree Legal Encyclopedia: Prerogative orders to Prohibition