"back then" meaning in English

{
  "lang": "English",
  "lang_code": "en",
  "pos": "prep_phrase",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Entries with translation boxes",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Spanish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Past",
          "orig": "en:Past",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "bold_text_offsets": [
            [
              193,
              202
            ]
          ],
          "ref": "2022 January 12, Nigel Harris, “Comment: Unhappy start to 2022”, in RAIL, number 948, page 3:",
          "text": "On the East and West Coast Main Lines in the 1950s/60s, for example, we saw the extinction of intermediate stations in order to create the same sort of accelerations that IRP is now promising. Back then, the priority was faster main line services, with wayside/intermediate stations paying the ultimate price.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "At that time, at the time referred to in the past."
      ],
      "id": "en-back_then-en-prep_phrase-RZskYY9q",
      "links": [
        [
          "At that time",
          "at that time"
        ]
      ],
      "related": [
        {
          "word": "back in the day"
        }
      ],
      "translations": [
        {
          "code": "es",
          "english": "nearer in time",
          "lang": "Spanish",
          "lang_code": "es",
          "sense": "at that time",
          "translation": "nearer in time",
          "word": "por ese entonces"
        },
        {
          "code": "es",
          "english": "further in time",
          "lang": "Spanish",
          "lang_code": "es",
          "sense": "at that time",
          "translation": "further in time",
          "word": "por aquel entonces"
        }
      ]
    }
  ],
  "word": "back then"
}

{
  "lang": "English",
  "lang_code": "en",
  "pos": "prep_phrase",
  "related": [
    {
      "word": "back in the day"
    }
  ],
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English prepositional phrases",
        "English terms with quotations",
        "Entries with translation boxes",
        "Pages with 1 entry",
        "Pages with entries",
        "Terms with Spanish translations",
        "en:Past"
      ],
      "examples": [
        {
          "bold_text_offsets": [
            [
              193,
              202
            ]
          ],
          "ref": "2022 January 12, Nigel Harris, “Comment: Unhappy start to 2022”, in RAIL, number 948, page 3:",
          "text": "On the East and West Coast Main Lines in the 1950s/60s, for example, we saw the extinction of intermediate stations in order to create the same sort of accelerations that IRP is now promising. Back then, the priority was faster main line services, with wayside/intermediate stations paying the ultimate price.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "At that time, at the time referred to in the past."
      ],
      "links": [
        [
          "At that time",
          "at that time"
        ]
      ]
    }
  ],
  "translations": [
    {
      "code": "es",
      "english": "nearer in time",
      "lang": "Spanish",
      "lang_code": "es",
      "sense": "at that time",
      "translation": "nearer in time",
      "word": "por ese entonces"
    },
    {
      "code": "es",
      "english": "further in time",
      "lang": "Spanish",
      "lang_code": "es",
      "sense": "at that time",
      "translation": "further in time",
      "word": "por aquel entonces"
    }
  ],
  "word": "back then"
}

{
  "called_from": "page/2530",
  "msg": "skipping string in the middle of translations: </table></div></div>\n\n",
  "path": [
    "back then"
  ],
  "section": "English",
  "subsection": "prepositional phrase",
  "title": "back then",
  "trace": ""
}