"external stimulus" meaning in English

{
  "forms": [
    {
      "form": "external stimuli",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "external stimuli"
      },
      "expansion": "external stimulus (plural external stimuli)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A signal (stimulus) that originates from outside an organism."
      ],
      "id": "en-external_stimulus-en-noun-muB479ZM",
      "links": [
        [
          "signal",
          "signal"
        ],
        [
          "stimulus",
          "stimulus"
        ]
      ]
    }
  ],
  "word": "external stimulus"
}

{
  "forms": [
    {
      "form": "external stimuli",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "external stimuli"
      },
      "expansion": "external stimulus (plural external stimuli)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A signal (stimulus) that originates from outside an organism."
      ],
      "links": [
        [
          "signal",
          "signal"
        ],
        [
          "stimulus",
          "stimulus"
        ]
      ]
    }
  ],
  "word": "external stimulus"
}