"only if" meaning in English

{
  "head_templates": [
    {
      "args": {},
      "expansion": "only if",
      "name": "en-con"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "conj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "derived": [
        {
          "word": "if and only if"
        }
      ],
      "examples": [
        {
          "text": "The company will succeed only if it has sufficient backing."
        },
        {
          "text": "1965 June 4, John W. Tukey, Data Analysis and the Frontiers of Geophysics, in Science New Series, 148(3675), page 1288, http://links.jstor.org/sici?sici=0036-8075%2819650604%293%3A148%3A3675%3C1283%3ADAATFO%3E2.0.CO%3B2-N\nThis is a somewhat paradoxical conclusion, and we can be happy to learn that it follows only if we can trust, precisely and in detail, the assumed way in which the probability of occurrence of a deviation decreases as the size of that deviation increases."
        },
        {
          "ref": "2005, Ellen Siever, Aaron Weber, Stephen Figgins, Robert Love, Arnold Robbins, Linux in a Nutshell, O'Reilly, page 802",
          "text": "This option is available only if the client supports it.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Not unless; used to introduce a necessary condition."
      ],
      "id": "en-only_if-en-conj-pP0yB~es",
      "links": [
        [
          "Not",
          "not"
        ],
        [
          "unless",
          "unless"
        ],
        [
          "necessary",
          "necessary"
        ],
        [
          "condition",
          "condition"
        ]
      ],
      "translations": [
        {
          "code": "fi",
          "lang": "Finnish",
          "sense": "not unless",
          "word": "vain, jos"
        },
        {
          "code": "hu",
          "lang": "Hungarian",
          "sense": "not unless",
          "word": "csak akkor"
        },
        {
          "code": "hu",
          "lang": "Hungarian",
          "sense": "not unless",
          "word": "csakis akkor"
        },
        {
          "code": "pl",
          "lang": "Polish",
          "sense": "not unless",
          "word": "tylko jeżeli"
        }
      ]
    }
  ],
  "word": "only if"
}

{
  "derived": [
    {
      "word": "if and only if"
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "only if",
      "name": "en-con"
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  "lang": "English",
  "lang_code": "en",
  "pos": "conj",
  "senses": [
    {
      "categories": [
        "English conjunctions",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English terms with quotations"
      ],
      "examples": [
        {
          "text": "The company will succeed only if it has sufficient backing."
        },
        {
          "text": "1965 June 4, John W. Tukey, Data Analysis and the Frontiers of Geophysics, in Science New Series, 148(3675), page 1288, http://links.jstor.org/sici?sici=0036-8075%2819650604%293%3A148%3A3675%3C1283%3ADAATFO%3E2.0.CO%3B2-N\nThis is a somewhat paradoxical conclusion, and we can be happy to learn that it follows only if we can trust, precisely and in detail, the assumed way in which the probability of occurrence of a deviation decreases as the size of that deviation increases."
        },
        {
          "ref": "2005, Ellen Siever, Aaron Weber, Stephen Figgins, Robert Love, Arnold Robbins, Linux in a Nutshell, O'Reilly, page 802",
          "text": "This option is available only if the client supports it.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Not unless; used to introduce a necessary condition."
      ],
      "links": [
        [
          "Not",
          "not"
        ],
        [
          "unless",
          "unless"
        ],
        [
          "necessary",
          "necessary"
        ],
        [
          "condition",
          "condition"
        ]
      ]
    }
  ],
  "translations": [
    {
      "code": "fi",
      "lang": "Finnish",
      "sense": "not unless",
      "word": "vain, jos"
    },
    {
      "code": "hu",
      "lang": "Hungarian",
      "sense": "not unless",
      "word": "csak akkor"
    },
    {
      "code": "hu",
      "lang": "Hungarian",
      "sense": "not unless",
      "word": "csakis akkor"
    },
    {
      "code": "pl",
      "lang": "Polish",
      "sense": "not unless",
      "word": "tylko jeżeli"
    }
  ],
  "word": "only if"
}