"but-" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "butyl"
      },
      "expansion": "butyl",
      "name": "m"
    },
    {
      "args": {
        "1": "en",
        "2": "grc",
        "3": "βούτυρος",
        "t": "butter"
      },
      "expansion": "Ancient Greek βούτυρος (boúturos, “butter”)",
      "name": "der"
    }
  ],
  "etymology_text": "From butyl. Ultimately from Ancient Greek βούτυρος (boúturos, “butter”).",
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "prefix",
        "head": "",
        "sort": ""
      },
      "expansion": "but-",
      "name": "head"
    },
    {
      "args": {},
      "expansion": "but-",
      "name": "en-prefix"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with topic categories using raw markup",
          "parents": [
            "Entries with topic categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Organic chemistry",
          "orig": "en:Organic chemistry",
          "parents": [
            "Chemistry",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "coordinate_terms": [
        {
          "word": "metho-"
        },
        {
          "word": "eth-"
        },
        {
          "word": "prop-"
        }
      ],
      "derived": [
        {
          "word": "butane"
        },
        {
          "word": "butanol"
        },
        {
          "word": "butyl"
        }
      ],
      "glosses": [
        "Denotes the presence of four carbon atoms in the parent chain when forming names of organic compounds."
      ],
      "id": "en-but--en-prefix-Ejpa4DpH",
      "links": [
        [
          "organic chemistry",
          "organic chemistry"
        ],
        [
          "carbon",
          "carbon"
        ],
        [
          "atom",
          "atom"
        ],
        [
          "parent chain",
          "parent chain"
        ],
        [
          "organic compound",
          "organic compound"
        ]
      ],
      "raw_glosses": [
        "(organic chemistry) Denotes the presence of four carbon atoms in the parent chain when forming names of organic compounds."
      ],
      "tags": [
        "morpheme"
      ],
      "topics": [
        "chemistry",
        "natural-sciences",
        "organic-chemistry",
        "physical-sciences"
      ]
    }
  ],
  "word": "but-"
}

{
  "coordinate_terms": [
    {
      "word": "metho-"
    },
    {
      "word": "eth-"
    },
    {
      "word": "prop-"
    }
  ],
  "derived": [
    {
      "word": "butane"
    },
    {
      "word": "butanol"
    },
    {
      "word": "butyl"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "butyl"
      },
      "expansion": "butyl",
      "name": "m"
    },
    {
      "args": {
        "1": "en",
        "2": "grc",
        "3": "βούτυρος",
        "t": "butter"
      },
      "expansion": "Ancient Greek βούτυρος (boúturos, “butter”)",
      "name": "der"
    }
  ],
  "etymology_text": "From butyl. Ultimately from Ancient Greek βούτυρος (boúturos, “butter”).",
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "prefix",
        "head": "",
        "sort": ""
      },
      "expansion": "but-",
      "name": "head"
    },
    {
      "args": {},
      "expansion": "but-",
      "name": "en-prefix"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "prefix",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English entries with topic categories using raw markup",
        "English lemmas",
        "English prefixes",
        "English terms derived from Ancient Greek",
        "English terms with non-redundant non-automated sortkeys",
        "en:Hydrocarbon chain prefixes",
        "en:Organic chemistry"
      ],
      "glosses": [
        "Denotes the presence of four carbon atoms in the parent chain when forming names of organic compounds."
      ],
      "links": [
        [
          "organic chemistry",
          "organic chemistry"
        ],
        [
          "carbon",
          "carbon"
        ],
        [
          "atom",
          "atom"
        ],
        [
          "parent chain",
          "parent chain"
        ],
        [
          "organic compound",
          "organic compound"
        ]
      ],
      "raw_glosses": [
        "(organic chemistry) Denotes the presence of four carbon atoms in the parent chain when forming names of organic compounds."
      ],
      "tags": [
        "morpheme"
      ],
      "topics": [
        "chemistry",
        "natural-sciences",
        "organic-chemistry",
        "physical-sciences"
      ]
    }
  ],
  "word": "but-"
}