Office: “Add to dictionary” option greyed out

I have helped someone with their Word (& PowerPoint) for not able to add custom words into Dictionary. When the user selected an word and right click, the option for Add to dictionary is greyed out like below picture.

Fix/Solution: Add a Custom Dictionary and select a language in Proofing options.

1. Click File –> Options
2. Select Proofing –> Custom Dictionaries
3. Select the CUSTOM.DIC and a Language (English (United States) in my case) if not selected. If you don’t see your language, add it.

4. That’s all. Click OK’s to close all dialog boxes. Your problem is fixed. You can now add words into custom dictionary.