Creating and selecting a custom user dictionary file
If your industry uses many technical terms that are not found in a standard spelling check dictionary, you can create a custom user dictionary file that contains the industry terminology for your business.
To create and select a custom user dictionary file
From the Tools menu, click Preferences.
On the Communication tab, click Spelling Preferences.
Under Select user dictionary, click New.
In the New User Dictionary dialog box, in the File name field, type a new file name with the extension .dic (such as "aerospace.dic"), and then click Open.
Click OK.