Examine source code of Meaning Of...

{
  "name": "Meaning Of...",
  "description": "Find the meaning of the word without leaving your current browser tab.",
  "version": "0.1.0",
  "manifest_version": 2,
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "Meaning Of...",
    "default_icon": {
      "48": "icons8-search-48.png",
      "96": "icons8-search-96.png"
    }
  },
  "icons": {
    "48": "icons8-search-48.png",
    "96": "icons8-search-96.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a2d9b2d0-5b9c-4828-a3ac-7bb4422a5b9f}"
    }
  }
}