retro

adj

1. Of, or relating to, the past, past times, or the way things were.

   “Scientists say that while the public may think of the moon as a problem solved and a bit retro – the place astronauts visited a half-dozen times way back before Watergate and then abandoned with a giant "meh" from mankind – in fact, lunar studies is a vibrant enterprise that is yielding a wealth of surprises.”

2. Affecting things past; retroactive, ex post facto.

noun

1. (uncountable)Past fashions or trends.
2. (abbreviation, alt-of, countable)Abbreviation of retrorocket.
3. (abbreviation, alt-of, countable)Abbreviation of retrospective.

   “Richard Leacock's 1981 film portrait, Louise Brooks, was shown during a retro of Ms. Brooks's films at the Walker Art Center.”

4. (countable, uncountable)A chess puzzle of retrograde analysis, requiring the solver to work out the history of moves leading to the position presented.