The most common word accepted in Mithraic historiography to refer to places of worship is “Mithraeum”. The historical sources, however, offer us a multitude of terms that diverge from this expression which could be evoking different realities and could be referring to other kind of cultic spaces. In this paper, we have collected all the mentions supported in the epigraphy and literary sources, to have a complete vision of all these terms. With these testimonies, we have revised the previous interpretations related to the use of these different names. The variety of them has little to do with location or period. Still, we propose that this terminological variation is related to the consideration that ancient Mithra’s followers had with the moment when they erected the cultic space. It is possible to connect the choice of the word “spelaeum” or “templum” with the first idea they had of what must be an “original Mithraic cave” if we consider the meaning of the verbs used by the dedicators in their inscriptions. The validity of this interpretation will allow for a better understanding of the symbolic universe in which the followers of Mithra moved, instead of the common acceptance of the modern word “mithraeum”