"sêr môr" meaning in Welsh

{
  "forms": [
    {
      "form": "seren fôr",
      "tags": [
        "singulative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f-p",
        "2": "seren fôr"
      },
      "expansion": "sêr môr f (collective, singulative seren fôr, not mutable)",
      "name": "cy-noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Welsh entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "lifeform",
          "langcode": "cy",
          "name": "Echinoderms",
          "orig": "cy:Echinoderms",
          "parents": [
            "Animals",
            "Lifeforms",
            "All topics",
            "Life",
            "Fundamental",
            "Nature"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "starfish"
      ],
      "id": "en-sêr_môr-cy-noun-N1W0F7D5",
      "links": [
        [
          "starfish",
          "starfish"
        ]
      ],
      "tags": [
        "collective",
        "feminine",
        "not-mutable"
      ],
      "wikipedia": [
        "cy:sêr môr"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˌseːr ˈmoːr/"
    },
    {
      "rhymes": "-oːr"
    }
  ],
  "word": "sêr môr"
}

{
  "forms": [
    {
      "form": "seren fôr",
      "tags": [
        "singulative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f-p",
        "2": "seren fôr"
      },
      "expansion": "sêr môr f (collective, singulative seren fôr, not mutable)",
      "name": "cy-noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Rhymes:Welsh/oːr",
        "Rhymes:Welsh/oːr/2 syllables",
        "Welsh collective nouns",
        "Welsh entries with incorrect language header",
        "Welsh feminine nouns",
        "Welsh lemmas",
        "Welsh multiword terms",
        "Welsh non-mutable terms",
        "Welsh nouns",
        "Welsh terms with IPA pronunciation",
        "cy:Echinoderms"
      ],
      "glosses": [
        "starfish"
      ],
      "links": [
        [
          "starfish",
          "starfish"
        ]
      ],
      "tags": [
        "collective",
        "feminine",
        "not-mutable"
      ],
      "wikipedia": [
        "cy:sêr môr"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˌseːr ˈmoːr/"
    },
    {
      "rhymes": "-oːr"
    }
  ],
  "word": "sêr môr"
}