You use Microsoft Word's spelling checker every day, and probably just as often encounter some of the tool's puzzling behavior. Do you know how to get rid of a word that you mistakenly added to its dictionary, for instance, or how to hide the red wiggly lines that appear all over your document?

The following ten tips will help you to work more efficiently in Word 2010, and they will even make you and your documents look smarter.

1. Control the 'Check Spelling as You Type' feature
This default feature reviews spelling within your document as you work, indicating with a red wiggly line any words that are missing from the spelling checker's dictionary. The feature can be distracting, but it's easy to disable. To do so, choose File, Options, Proofing, click the Check spelling as you type checkbox to clear it and reverse the current setting, and then click OK.

2. Check foreign-language spelling
Word isn't naturally bilingual, but you can train it to process more than one language at a time. Ordinarily, when you're working on a document that includes text in, say, French, Word likely won't recognize the other language if you've set your primary language to U.S. English; in this case, Word will add wiggly lines under the assorted foreign words, suggesting that they are all misspellings.

You can avoid that situation by setting Word to check the French text using a French word list. To arrange this, select the text in French (or whatever foreign language you're using), and click the Review tab on the Ribbon toolbar. Then click Language and choose Set Language in the Proofing group of buttons. The Language dialog box will appear. Here you should click the language to use for the selected text; the listed languages displaying checkmark icons are available for use in checking spelling. Click OK to finish.

3. Add unusual words to the dictionary
If you know ahead of time that you will be using some unusual words, and if you do not want Word to report them as possible misspellings, you can add them to the dictionary.

Choose File, Options, Proofing, and click Custom Dictionaries. Click the custom.dic file--or the name of the dictionary to add the words to, if you are using a special dictionary--and click Edit Word List. Type a word, and click Add. When you're done, click OK to exit the dictionary.

Adding words one at a time is sensible if you have only a few. But if you have a long list of words to add, it's best to do so by editing the dictionary file itself.

First, from the Custom Dictionaries dialog box, make a note of the file-path entry that shows where the custom.dic file is located. Then launch a plain-text editor such as Notepad or WordPad, and use it to open the custom.dic file. Type or paste your words, one word per line, into the document and then save it. Word will automatically sort the items into alphabetical order when it next uses the file.

4. Remove misspellings in the Spelling Checker
If you add a misspelled word to the dictionary by accident, Word won't identify it as misspelled until you remove it.

Choose File, Options, Proofing, and click Custom Dictionaries. Select the default dictionary in the list; typically this is the custom.dic file. Click Edit Word List to open the custom.dic dialog box, which contains a list of words you have added to Word's custom dictionary. Scroll down the list, click the errant word, and then click Delete and Close. In the future, if you use this misspelling in a document, Word will properly flag it as a mistake.

5. Determine what the Spelling Checker checks
Depending on the type of work you do, you may discover that Word either finds errors where none exist, or fails to catch the embarrassing errors you do make. For some terms, such as email addresses, URLs, or items containing numbers, you can decide whether Word checks their spelling or leaves them alone.