Looking up words easily in the dictionary

Would it be possible for an entry to be installed on the menu that shows up when I highlight a word, so that I can look up the word on a dictionary, for example from an installed app such as Merriam-Webster dictionary. The app could show the definition inside a bubble. If course, the installed app would have to support this, and install the behavior onto the operating system UI. How can I achieve the behavior I'm looking for? Thanks.