"rétro-" meaning in French

{
  "etymology_templates": [
    {
      "args": {
        "1": "fr",
        "2": "la",
        "3": "retrō"
      },
      "expansion": "Learned borrowing from Latin retrō",
      "name": "lbor"
    }
  ],
  "etymology_text": "Learned borrowing from Latin retrō. Compare arrière.",
  "head_templates": [
    {
      "args": {},
      "expansion": "rétro-",
      "name": "fr-prefix"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "French entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "retro-, back, behind"
      ],
      "id": "en-rétro--fr-prefix-Oxlp2D8U",
      "links": [
        [
          "retro-",
          "retro-"
        ],
        [
          "back",
          "back"
        ],
        [
          "behind",
          "behind"
        ]
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ʁe.tʁo/"
    }
  ],
  "word": "rétro-"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "fr",
        "2": "la",
        "3": "retrō"
      },
      "expansion": "Learned borrowing from Latin retrō",
      "name": "lbor"
    }
  ],
  "etymology_text": "Learned borrowing from Latin retrō. Compare arrière.",
  "head_templates": [
    {
      "args": {},
      "expansion": "rétro-",
      "name": "fr-prefix"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        "French 2-syllable words",
        "French entries with incorrect language header",
        "French learned borrowings from Latin",
        "French lemmas",
        "French prefixes",
        "French terms borrowed from Latin",
        "French terms derived from Latin",
        "French terms with IPA pronunciation",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "retro-, back, behind"
      ],
      "links": [
        [
          "retro-",
          "retro-"
        ],
        [
          "back",
          "back"
        ],
        [
          "behind",
          "behind"
        ]
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ʁe.tʁo/"
    }
  ],
  "word": "rétro-"
}