retro [1960s] The fashion term retro is from French rétro, an abbreviation of rétrograde ‘retrograde’[LME]. This was originally a term in astronomy referring to planets appearing to move in a direction from east to west. It comes from Latin retrogradus, from retro ‘backwards’ and gradus ‘step’. Retro- is also the source of words such as retrospect [E17th] from Latin retrospicere ‘look back’.

Latin retro became rere in Old French, then arrière ‘behind’, which was adopted into English. The phrase th’arrear ‘the back’ was mis-analysed as ‘the rear’ and the ‘a’ at the beginning of the word dropped to become rear [ME]. It was used colloquially to mean ‘buttocks’ from the early 18th century. The other rear, ‘to raise up’ and its close relative rise, both Old English, come from a Germanic root, with raise, a Middle English introduction from Old Norse coming from the same source.