lo·cum te·nens 
(lōkəm′ tēnĕnz′, tĕnənz)
(lōkəm′ tēnĕnz′, tĕnənz)n. pl. locum te·nen·tes (tə-nĕntēz)
A person, especially a physician or cleric, who substitutes temporarily for another.
[Medieval Latin locum tenēns : Latin locum, accusative of locus, place + Latin tenēns, present participle of tenēre, to hold.]