Starting with Microsoft Edge Canary version 90.0.806.0 and higher, Microsoft has added a built-in dictionary feature to Define selected words while reading a PDF document in Microsoft Edge. Define will be available in the full context menu and quick menu when selecting words in PDFs.
The definition of the selected word(s) will show in a mini flyout menu with a brief description. if needed, you can select to see more details in a sidebar.
This tutorial will show you how to add or remove the Define smart action in the full context menu and quick menu while reading PDF files opened in the Chromium based Microsoft Edge.