All applications that are apple-scriptable have a "dictionary" of terms as part of the application itself. To access a dictionary open AppleScript Editor, under the File menu choose "open dictionary", and then choose the application.
A second way would be to drag/drop the application onto the AppleScript Editor icon in the dock or applications folder.
A third way... under the Window menu in AppleScript Editor choose "Library". That window is a quick-access tool to access the dictionaries of various applications. You can click the "+" button to add applications not in that list. Double-click an application in the list to access its dictionary.
A 4th way... if AppleScript Editor and the application you are interested in are both in the dock, you can command-drag the application's dock icon onto the AppleScript Editor's dock icon.