retro

Retro is an adverb of place and direction, "backwards, to the rear", built on the same re- that prefixes hundreds of Latin verbs. It does not take a case in classical prose; where later texts use it as a preposition with the accusative, that is a medieval extension.

Keep it apart from rursus, which is "again, once more" in time rather than "backwards" in space, and from retrorsum, the emphatic "back the other way". The famous vade retro, "get back", comes from the Vulgate. Latin also uses retro of time, "in the past", which is the ancestor of the English adjective retro; and the prefix went on to produce retrograde, retrospect, retreat and retribution, none of which needed a Roman to think of them.