The prefix "retro-" has several synonyms that can be used in different contexts. Some of the common synonyms for "retro-" are vintage, old-fashioned, classic, antique, nostalgic, retrograde, and historic. Vintage refers to something old but still in good condition and valuable. Old-fashioned means something that is no longer in vogue or popular. Classic relates to something timeless and elegant. Antique refers to something rare and valuable, usually more than a hundred years old. Nostalgic evokes feelings of longing for the past. Retrograde means an action or situation that takes things backward. Finally, historic refers to something significant or memorable from the past.