"nm" meaning in uni

{
  "categories": [
    {
      "kind": "other",
      "name": "Προέλευση λέξεων από τα αγγλικά (διεθνείς όροι)",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_text": "nm < αγγλική nanometer",
  "forms": [
    {
      "form": "nm",
      "source": "header"
    }
  ],
  "lang": "uni",
  "lang_code": "uni",
  "pos": "abbrev",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Μαθηματικά (διεθνείς όροι)",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Νεολογισμοί (διεθνείς όροι)",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Φυσική (διεθνείς όροι)",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "νανόμετρο"
      ],
      "id": "el-nm-uni-abbrev-qifK5FpZ",
      "raw_tags": [
        "νεολογισμός",
        "μαθηματικά",
        "φυσική"
      ],
      "tags": [
        "neologism"
      ],
      "topics": [
        "mathematics",
        "physics"
      ]
    }
  ],
  "word": "nm"
}

{
  "categories": [
    "Προέλευση λέξεων από τα αγγλικά (διεθνείς όροι)"
  ],
  "etymology_text": "nm < αγγλική nanometer",
  "forms": [
    {
      "form": "nm",
      "source": "header"
    }
  ],
  "lang": "uni",
  "lang_code": "uni",
  "pos": "abbrev",
  "senses": [
    {
      "categories": [
        "Μαθηματικά (διεθνείς όροι)",
        "Νεολογισμοί (διεθνείς όροι)",
        "Φυσική (διεθνείς όροι)"
      ],
      "glosses": [
        "νανόμετρο"
      ],
      "raw_tags": [
        "νεολογισμός",
        "μαθηματικά",
        "φυσική"
      ],
      "tags": [
        "neologism"
      ],
      "topics": [
        "mathematics",
        "physics"
      ]
    }
  ],
  "word": "nm"
}