The built-in Dictionary app in macOS is hardly the sexiest piece of software out there, but it is a crucially overlooked resource. When combined with the context menu’s “Look Up” function, it makes both learning words and using words correctly far easier. And for folks learning another language, it’s crucial to getting translations right. It’s already on your Mac; you just need to use it.
The easiest way to access the information stored in Dictionary is through a right-click. Select a word, then right-click on it. You’ll see “Look up ‘word'” as a context menu option. Select that and a contextual popup will appear over the highlighted word, over a definition or even a preview of the associated Wikipedia page.
You can also open the Dictionary app from “/Applications/Dictionary.app” or through Spotlight. From there you can search any dictionary specifically and access the thesaurus, perhaps the least-understood and most poorly used tool for writers of all skill levels. Quick tip for proper thesaurus use: remember that synonyms in a thesaurus are not perfect replacements. You still need to know the definition and connotation of the word before dropping it into your writing.
Adding Dictionaries to the Dictionary App
Dictionaries can be added from the library of available dictionaries. There are dictionaries for every language supported by macOS, as well as a number of additional English dictionaries that are useful to writers and students.
Open the Dictionary app’s preferences (“Dictionary -> Preferences” in the menu bar or Command + ' on your keyboard). This reveals a large list of all the available dictionaries within the application.
Select the dictionaries you want to appear by checking the boxes next to their names. Dictionaries are arranged alphabetically based on their language.
At the bottom you’ll find a few additional English dictionaries and thesauri, which can be quite useful to students and writers.
Changing Dictionary Names
Many of the dictionaries have unhelpfully short titles. By renaming dictionaries, we can see the relevant information about all the installed dictionaries at once.
To rename a dictionary, right-click on the dictionary in the toolbar and choose “Edit Label” from the context menu.
Type the dictionary’s new name in the text box and click “OK” to apply the change.
Importing Custom Dictionaries
Theoretically, custom dictionaries can be imported in the Dictionary app. That is, if you can find one. Many of the websites that hosted custom dictionaries are now defunct.
Dictionary files are stored in “~/Library/Dictionaries,” which can be accessed directly from Finder or by choosing “File -> Open Dictionaries Folder” in the Dictionary app.
Once you’ve found a dictionary in the “.dictionary” format, you can place it in that folder. The Dictionary app will automatically load it the next time it’s opened.
There are not many active websites that offer dictionary files for download, unfortunately. The major ones, like StarDict, have closed up shop for one reason or another. As of this writing, clasqm has some dictionaries available for multiple foreign languages and are available for download on his website.
Conclusion: Creating Dictionaries
There are also instructions for converting other types of dictionaries to the Apple format, which are complex but functional. This allows you to convert Babylon (BGL) dictionaries, of which there is an abundance. Find the library of Babylon dictionaries here. We can confirm that a commonly-used tool for this process, DictUnifier, does not function in modern versions of macOS.
A third-party program, Dictionaries.io, can add many multilingual spellchecking dictionaries to Dictionary.app. It is paid software, but if you’re frequently working with multiple languages, it’s likely the best dictionary tool for the job.