"polyalphabetic" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "poly",
        "3": "alphabetic"
      },
      "expansion": "poly- + alphabetic",
      "name": "prefix"
    }
  ],
  "etymology_text": "poly- + alphabetic",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "polyalphabetic (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "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 terms prefixed with poly-",
          "parents": [],
          "source": "w"
        }
      ],
      "derived": [
        {
          "word": "polyalphabetically"
        }
      ],
      "glosses": [
        "Describing a substitution cipher in which plaintext letters in different positions are enciphered using different substitution alphabets."
      ],
      "id": "en-polyalphabetic-en-adj-Pk6jOY3-",
      "links": [
        [
          "substitution",
          "substitution"
        ],
        [
          "cipher",
          "cipher"
        ],
        [
          "plaintext",
          "plaintext"
        ],
        [
          "letter",
          "letter"
        ],
        [
          "alphabet",
          "alphabet"
        ]
      ],
      "tags": [
        "not-comparable"
      ],
      "wikipedia": [
        "polyalphabetic cipher"
      ]
    }
  ],
  "word": "polyalphabetic"
}

{
  "derived": [
    {
      "word": "polyalphabetically"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "poly",
        "3": "alphabetic"
      },
      "expansion": "poly- + alphabetic",
      "name": "prefix"
    }
  ],
  "etymology_text": "poly- + alphabetic",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "polyalphabetic (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        "English adjectives",
        "English entries with incorrect language header",
        "English lemmas",
        "English terms prefixed with poly-",
        "English uncomparable adjectives"
      ],
      "glosses": [
        "Describing a substitution cipher in which plaintext letters in different positions are enciphered using different substitution alphabets."
      ],
      "links": [
        [
          "substitution",
          "substitution"
        ],
        [
          "cipher",
          "cipher"
        ],
        [
          "plaintext",
          "plaintext"
        ],
        [
          "letter",
          "letter"
        ],
        [
          "alphabet",
          "alphabet"
        ]
      ],
      "tags": [
        "not-comparable"
      ],
      "wikipedia": [
        "polyalphabetic cipher"
      ]
    }
  ],
  "word": "polyalphabetic"
}