pro tem / prō ˈtem/ • adv. & adj. for the time being: [as adv.] a printer that Marisa could use pro tem | [as adj.] a pro tem committee | [as adj.] the president pro tem of the Senate. ORIGIN: abbreviation of Latin pro tempore.
[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.