"kas" meaning in Estonian

{
  "etymology_text": "Derived from kaasas.",
  "head_templates": [
    {
      "args": {
        "1": "et",
        "2": "particle"
      },
      "expansion": "kas",
      "name": "head"
    }
  ],
  "lang": "Estonian",
  "lang_code": "et",
  "pos": "particle",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Estonian entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Estonian particles",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 29 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "english": "Has (s)he arrived?",
          "text": "Kas ta on saabunud?",
          "type": "example"
        }
      ],
      "glosses": [
        "Used to introduce a yes-or-no question."
      ],
      "id": "en-kas-et-particle-m1-H31Ot",
      "related": [
        {
          "word": "kas või"
        },
        {
          "word": "kasvõi"
        }
      ]
    }
  ],
  "word": "kas"
}

{
  "etymology_text": "Derived from kaasas.",
  "head_templates": [
    {
      "args": {
        "1": "et",
        "2": "particle"
      },
      "expansion": "kas",
      "name": "head"
    }
  ],
  "lang": "Estonian",
  "lang_code": "et",
  "pos": "particle",
  "related": [
    {
      "word": "kas või"
    },
    {
      "word": "kasvõi"
    }
  ],
  "senses": [
    {
      "categories": [
        "Estonian entries with incorrect language header",
        "Estonian lemmas",
        "Estonian particles",
        "Estonian terms with usage examples",
        "Pages with 29 entries",
        "Pages with entries"
      ],
      "examples": [
        {
          "english": "Has (s)he arrived?",
          "text": "Kas ta on saabunud?",
          "type": "example"
        }
      ],
      "glosses": [
        "Used to introduce a yes-or-no question."
      ]
    }
  ],
  "word": "kas"
}