New Feature: You can now change the setting to disable launching the dictionary from double-clicking. This is a third-party add-on for the Merriam-Webster's Learner's Dictionary with Audio.

Double-click on a word to look it up (or highlight it and right-click).
To bookmark an entry, click on the star at the lower right. The bookmark will be saved in a folder under the Other Bookmarks section. You can rename or move the folder as you see fit.
To visit an entry at learnersdictionary.com in a new tab, click on the Merriam-Webster logo in the upper right.

Reviews and feedback are appreciated! Thanks!