Used postpositively: subsequent to the existence of, or logically posterior to, something else.
Chiefly used with reference to theories according to which universal concepts and terms logically presuppose particulars from which they are abstracted..
Origin
Late 19th century; earliest use found in Mind. From classical Latin post rem, lit. ‘after the thing’, in post-classical Latin used with reference to different kinds of universal from post after + rem, accusative of rēs thing.