"αθροίσεως" meaning in Greek

{
  "forms": [
    {
      "form": "athroíseos",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "2": "noun form",
        "g": "f",
        "g2": "",
        "g3": "",
        "head": "",
        "sort": ""
      },
      "expansion": "αθροίσεως • (athroíseos) f",
      "name": "head"
    },
    {
      "args": {
        "1": "f"
      },
      "expansion": "αθροίσεως • (athroíseos) f",
      "name": "el-noun-form"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Greek entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "form_of": [
        {
          "extra": "áthroisi",
          "word": "άθροιση"
        }
      ],
      "glosses": [
        "Genitive singular form of άθροιση (áthroisi)."
      ],
      "id": "en-αθροίσεως-el-noun-R9mO4psA",
      "links": [
        [
          "Genitive",
          "genitive"
        ],
        [
          "singular",
          "singular"
        ],
        [
          "άθροιση",
          "άθροιση#Greek"
        ]
      ],
      "tags": [
        "form-of",
        "genitive",
        "singular"
      ]
    }
  ],
  "word": "αθροίσεως"
}

{
  "forms": [
    {
      "form": "athroíseos",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "2": "noun form",
        "g": "f",
        "g2": "",
        "g3": "",
        "head": "",
        "sort": ""
      },
      "expansion": "αθροίσεως • (athroíseos) f",
      "name": "head"
    },
    {
      "args": {
        "1": "f"
      },
      "expansion": "αθροίσεως • (athroíseos) f",
      "name": "el-noun-form"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Greek entries with incorrect language header",
        "Greek non-lemma forms",
        "Greek noun forms"
      ],
      "form_of": [
        {
          "extra": "áthroisi",
          "word": "άθροιση"
        }
      ],
      "glosses": [
        "Genitive singular form of άθροιση (áthroisi)."
      ],
      "links": [
        [
          "Genitive",
          "genitive"
        ],
        [
          "singular",
          "singular"
        ],
        [
          "άθροιση",
          "άθροιση#Greek"
        ]
      ],
      "tags": [
        "form-of",
        "genitive",
        "singular"
      ]
    }
  ],
  "word": "αθροίσεως"
}