"sea day" meaning in English

{
  "forms": [
    {
      "form": "sea days",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "sea day (plural sea days)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2006, Heidi Sarna, Cruise Vacations For Dummies, page 85",
          "text": "Sea days on Alaskan cruises are a bit more destination-oriented, with the ships visiting glaciers and areas known for exemplary whale-watching.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A day on which a cruise ship remains at sea all day (i.e. passengers cannot leave the ship)."
      ],
      "id": "en-sea_day-en-noun-MHqOBkxl",
      "synonyms": [
        {
          "word": "sea-day"
        },
        {
          "word": "seaday"
        }
      ]
    }
  ],
  "word": "sea day"
}

{
  "forms": [
    {
      "form": "sea days",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "sea day (plural sea days)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "2006, Heidi Sarna, Cruise Vacations For Dummies, page 85",
          "text": "Sea days on Alaskan cruises are a bit more destination-oriented, with the ships visiting glaciers and areas known for exemplary whale-watching.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A day on which a cruise ship remains at sea all day (i.e. passengers cannot leave the ship)."
      ]
    }
  ],
  "synonyms": [
    {
      "word": "sea-day"
    },
    {
      "word": "seaday"
    }
  ],
  "word": "sea day"
}