"ς" meaning in Greek

{
  "forms": [
    {
      "form": "Σ",
      "tags": [
        "uppercase"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "2": "letter",
        "3": "lowercase",
        "4": "",
        "5": "uppercase",
        "6": "Σ"
      },
      "expansion": "ς • (s) (lowercase, uppercase Σ)",
      "name": "head"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "character",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Greek entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The lower case letter sigma (σίγμα τελικό (sígma telikó)) of the Greek alphabet when used as the final letter in a word (a final sigma). In all other positions in a word the normal sigma (σ (s)) must be used."
      ],
      "id": "en-ς-el-character-jLw8bd2T",
      "links": [
        [
          "lower case",
          "lower case"
        ],
        [
          "sigma",
          "sigma"
        ],
        [
          "σίγμα τελικό",
          "σίγμα τελικό#Greek"
        ],
        [
          "Greek alphabet",
          "Greek alphabet"
        ],
        [
          "final sigma",
          "final sigma"
        ],
        [
          "σ",
          "σ#Greek"
        ]
      ],
      "tags": [
        "letter",
        "lowercase"
      ]
    }
  ],
  "word": "ς"
}

{
  "forms": [
    {
      "form": "Σ",
      "tags": [
        "uppercase"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "2": "letter",
        "3": "lowercase",
        "4": "",
        "5": "uppercase",
        "6": "Σ"
      },
      "expansion": "ς • (s) (lowercase, uppercase Σ)",
      "name": "head"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "character",
  "senses": [
    {
      "categories": [
        "Greek entries with incorrect language header",
        "Greek lemmas",
        "Greek letters"
      ],
      "glosses": [
        "The lower case letter sigma (σίγμα τελικό (sígma telikó)) of the Greek alphabet when used as the final letter in a word (a final sigma). In all other positions in a word the normal sigma (σ (s)) must be used."
      ],
      "links": [
        [
          "lower case",
          "lower case"
        ],
        [
          "sigma",
          "sigma"
        ],
        [
          "σίγμα τελικό",
          "σίγμα τελικό#Greek"
        ],
        [
          "Greek alphabet",
          "Greek alphabet"
        ],
        [
          "final sigma",
          "final sigma"
        ],
        [
          "σ",
          "σ#Greek"
        ]
      ],
      "tags": [
        "letter",
        "lowercase"
      ]
    }
  ],
  "word": "ς"
}