"dyfrllys blaenllym" meaning in Welsh

{
  "head_templates": [
    {
      "args": {
        "1": "m"
      },
      "expansion": "dyfrllys blaenllym m",
      "name": "cy-noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Welsh entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "lifeform",
          "langcode": "cy",
          "name": "Water plants",
          "orig": "cy:Water plants",
          "parents": [
            "Plants",
            "Lifeforms",
            "All topics",
            "Life",
            "Fundamental",
            "Nature"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "fennel pondweed (Stuckenia pectinata syn. Potamogeton pectinatus)"
      ],
      "id": "en-dyfrllys_blaenllym-cy-noun-0xyo-rWg",
      "synonyms": [
        {
          "word": "dyfrllys danheddog"
        },
        {
          "word": "dyfrllys gwrychddail"
        }
      ],
      "tags": [
        "masculine"
      ]
    }
  ],
  "word": "dyfrllys blaenllym"
}

{
  "head_templates": [
    {
      "args": {
        "1": "m"
      },
      "expansion": "dyfrllys blaenllym m",
      "name": "cy-noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Entries missing English vernacular names of taxa",
        "Entries using missing taxonomic name (species)",
        "Pages with 1 entry",
        "Pages with entries",
        "Welsh countable nouns",
        "Welsh entries with incorrect language header",
        "Welsh lemmas",
        "Welsh masculine nouns",
        "Welsh multiword terms",
        "Welsh nouns",
        "cy:Water plants"
      ],
      "glosses": [
        "fennel pondweed (Stuckenia pectinata syn. Potamogeton pectinatus)"
      ],
      "tags": [
        "masculine"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "dyfrllys danheddog"
    },
    {
      "word": "dyfrllys gwrychddail"
    }
  ],
  "word": "dyfrllys blaenllym"
}