"sub-" meaning in Catalan

{
  "etymology_templates": [
    {
      "args": {
        "1": "ca",
        "2": "la",
        "3": "sub"
      },
      "expansion": "Borrowed from Latin sub",
      "name": "bor+"
    }
  ],
  "etymology_text": "Borrowed from Latin sub.",
  "head_templates": [
    {
      "args": {
        "1": "ca",
        "2": "prefix"
      },
      "expansion": "sub-",
      "name": "head"
    }
  ],
  "lang": "Catalan",
  "lang_code": "ca",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Catalan entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages using catfix",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 13 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "sub-"
      ],
      "id": "en-sub--ca-prefix-TpKaUKvR",
      "links": [
        [
          "sub-",
          "sub-#English"
        ]
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "sub-"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "ca",
        "2": "la",
        "3": "sub"
      },
      "expansion": "Borrowed from Latin sub",
      "name": "bor+"
    }
  ],
  "etymology_text": "Borrowed from Latin sub.",
  "head_templates": [
    {
      "args": {
        "1": "ca",
        "2": "prefix"
      },
      "expansion": "sub-",
      "name": "head"
    }
  ],
  "lang": "Catalan",
  "lang_code": "ca",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        "Catalan entries with incorrect language header",
        "Catalan lemmas",
        "Catalan prefixes",
        "Catalan terms borrowed from Latin",
        "Catalan terms derived from Latin",
        "Pages using catfix",
        "Pages with 13 entries",
        "Pages with entries"
      ],
      "glosses": [
        "sub-"
      ],
      "links": [
        [
          "sub-",
          "sub-#English"
        ]
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "sub-"
}