"isotone" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Lemmes en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Noms communs en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "forms": [
    {
      "form": "isotones",
      "ipas": [
        "\\ˈai.səʊ.təʊnz\\"
      ],
      "tags": [
        "plural"
      ]
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Nom commun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Exemples en anglais",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Exemples en anglais à traduire",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Lexique en anglais de la physique",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "Linus Pauling, Barclay Kamb, Linus Pauling: Physical sciences, 2001, citant Physical Review Lettersvol. 15, no. 22, 29 novembre 1965",
          "text": "Evidence about the nature of the transition is provided by the observed proton numbers of the stable highest-Z isotones. A useful empirical rule is that the largest proton number for a set of stable isotones is equal to the neutron number of the mantle."
        }
      ],
      "glosses": [
        "Isotone."
      ],
      "id": "fr-isotone-en-noun-u~ip7xVv",
      "tags": [
        "physical"
      ]
    }
  ],
  "word": "isotone"
}

{
  "categories": [
    "Lemmes en anglais",
    "Noms communs en anglais",
    "anglais"
  ],
  "forms": [
    {
      "form": "isotones",
      "ipas": [
        "\\ˈai.səʊ.təʊnz\\"
      ],
      "tags": [
        "plural"
      ]
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Nom commun",
  "senses": [
    {
      "categories": [
        "Exemples en anglais",
        "Exemples en anglais à traduire",
        "Lexique en anglais de la physique"
      ],
      "examples": [
        {
          "ref": "Linus Pauling, Barclay Kamb, Linus Pauling: Physical sciences, 2001, citant Physical Review Lettersvol. 15, no. 22, 29 novembre 1965",
          "text": "Evidence about the nature of the transition is provided by the observed proton numbers of the stable highest-Z isotones. A useful empirical rule is that the largest proton number for a set of stable isotones is equal to the neutron number of the mantle."
        }
      ],
      "glosses": [
        "Isotone."
      ],
      "tags": [
        "physical"
      ]
    }
  ],
  "word": "isotone"
}