If an application is not running and you’ve never worked with it before, and if you are not currently targeting it in a script, you can open its dictionary in the following ways:

• Choose File > Open. This brings up a dialog where you can choose anything. If what you choose is an application or scripting addition, its dictionary will open.
• Choose File > Open Dictionary > Application. This brings up a dialog where you can choose an application or scripting addition to open its dictionary.
• Locate the application or scripting addition in the Finder and drag its icon onto Script Debugger’s icon (possibly onto Script Debugger’s icon in the Dock).
• Locate the application or scripting addition in the Finder and drag its icon onto a Script Debugger script window. Script Debugger will put up a dialog asking what you want to do. One of the options is to open the application’s dictionary.