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How to add and remove words in a custom dictionary in Outlook?

Author: Kelly Last Modified: 2025-04-11

When typing specialized terms like "Kutools for Outlook" in an email, Outlook might not recognize these terms, flagging them as spelling errors with a red wavy line. This occurs because Outlook's default dictionary doesn't include specialized or technical names. To prevent this, you can add such words to your custom dictionary. This guide will show you how to proactively add and remove words from the custom dictionary in Outlook, and also how to add words to the dictionary easily while composing an email.

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Add and remove words in the custom dictionary in Outlook

Add words in a custom dictionary when composing an email message


Add and remove words in the custom dictionary in Outlook

Add special names and terms into the custom dictionary in Outlook in advance, preventing marking them as spelling mistakes in your email messages.

Step 1: Click "File" > "Options".

Step 2: Click "Mail" in the left bar.

Step 3: Click "Spelling and Autocorrect" button in the "Compose messages" section.

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Step 4: Click "Custom Dictionaries" button in the Editor Options dialog box.

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Step 5: Select and highlight "Custom.DIC (Default)" in the "Dictionary List" box, and click the "Edit Word List" button.

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Step 6: In the "Word(s):" box type the words you will add to your custom dictionary, and click the "Add" button.

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Delete words from dictionary: If you need to remove words from the custom dictionary, please select the words in the "Dictionary:" box, and then click the "Delete" button.

Step 7: Click the "OK" buttons in each dialog box.

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Add words in a custom dictionary when composing an email message

In addition to adding words to the custom dictionary in advance, you can also add words to your custom dictionary when you are composing an email message.

Step 1: Run the Spelling feature in the Message Window:

  1. In the new message dialog, click the "Spelling & Grammar" button in the "Proofing" group on the "Review" tab.
  2. Press the "F7" key.

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Step 2: In the Spelling and Grammar: English (U.S.) dialog box, click the "Add to Dictionary" button.

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Step 3: Now a prompt dialog pops up to tell you the success of adding words, please click "OK" to close it.

Alternatively, you can right-click on words underlined with a red wavy line and select "Add to Dictionary" from the context menu.

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