pro tem /ˌprəʊ ˈtem $ ˌproʊ-/ BrE AmE ( also pro tem‧po‧re /-ˈtempəreɪ/) adjective [only after noun] formal
[ Date: 1800-1900 ; Language: Latin ; Origin: pro tempore 'for the time' ]
happening or existing now, but only for a short time:
the president pro tem of the Senate