"masa atómica" meaning in Spanish

{
  "forms": [
    {
      "form": "masas atómicas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "masa atómica f (plural masas atómicas)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Spanish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "es",
          "name": "Physics",
          "orig": "es:Physics",
          "parents": [
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "atomic mass (the mass of an atom)"
      ],
      "id": "en-masa_atómica-es-noun-ATmr~mCG",
      "links": [
        [
          "atomic mass",
          "atomic mass"
        ]
      ],
      "related": [
        {
          "word": "peso atómico"
        }
      ],
      "tags": [
        "feminine"
      ]
    }
  ],
  "word": "masa atómica"
}

{
  "forms": [
    {
      "form": "masas atómicas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "masa atómica f (plural masas atómicas)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "related": [
    {
      "word": "peso atómico"
    }
  ],
  "senses": [
    {
      "categories": [
        "Spanish countable nouns",
        "Spanish entries with incorrect language header",
        "Spanish feminine nouns",
        "Spanish lemmas",
        "Spanish multiword terms",
        "Spanish nouns",
        "es:Physics"
      ],
      "glosses": [
        "atomic mass (the mass of an atom)"
      ],
      "links": [
        [
          "atomic mass",
          "atomic mass"
        ]
      ],
      "tags": [
        "feminine"
      ]
    }
  ],
  "word": "masa atómica"
}