prior

Prior, prius is a comparative with no positive behind it. The series runs prior against posterior for two things, and tops out at primus, "first of many", so if a text says prior it is usually contrasting exactly two. Third declension, two terminations, ablative singular priore rather than priori in most classical prose.

The neuter prius doubles as an adverb, "earlier, sooner", and prius quam runs together as priusquam, "before". Monastic Latin then does something plain with it: the prior is simply the one who comes before, the officer under the abbot, and a priory is his house. English takes prior, priority, a priori and the ecclesiastical prior from the same short word.