The prefix ‘retro-‘ derives from Latin, meaning backward or behind.
In English, it is used to indicate a backward or retrospective movement,
or refers to something old-fashioned, revived or reminiscent of the past:
- Retroactive: applying or affecting something from a past date or time
- Retrograde: moving or tending backward; opposite to the usual or desired direction
- Retrocession: the act of ceding or giving back something previously acquired
- Retrofit: to add or modify something in an older system or structure, to make it more up-to-date or efficient

‘Retro’ has itself become a word on its own:
- retro dressing (adverb)
- retro fashioon (adjective)

Though ‘retri-‘ isn’t a prefix in the standard sense of the term, since
it derives from the Latin "retrahere," meaning to draw back or to regain,
it is hinted in words like:

- Retrieval: act of bringing or getting (sth.) back; to regain possession (of sth.)
- Retribution: punishment or penalty inflicted for wrongdoings; act of seeking revenge or repayment.

The prefix ‘re-‘ too means the same:
- Retract: withdraw or take back something that has been said, written, or done
- Retrace: go back along the same path or route previously taken

Typically ‘retr-‘ implies a sense of going back or returning to a previous state or action.