pro tempro tem /ˌprəʊ ˈtem $ ˌproʊ-/ (also pro tem‧po‧re /-ˈtempəreɪ/) adjective [only after noun] formal 
happening or existing now, but only for a short time: 
the president pro tem of the Senate
happening or existing now, but only for a short time: the president pro tem of the Senate