Office 2010 doesn’t recognize the word “symbology“

The folks at Microsoft acknowledge that gaps will exist in their basic dictionary:

"When you use the spelling checker, it compares the words in your document with those in the main dictionary, the one that ships with Microsoft Office. The main dictionary contains most common words, but it might not include proper names, technical terms, or acronyms that you use. In addition, some words might be capitalized differently in the main dictionary than what you want in your document. Adding such words or capitalization to a custom dictionary prevents the spelling checker from flagging them as mistakes." [from the Word help files, using "add to dictionary" as the search term]

If you're just concerned about one word, you can simply right-click it and select "Add to Dictionary" and the "flagging" (the red squiggle underline) will go away for good. If you have several words you want to add to the custom dictionary, go to File>Options>Proofing and click on "Custom Dictionaries." That will allow you to add and delete words at will (but only in the custom dictionaries).

Don't be surprised at the omissions, odd suggestions, and dubious corrections that MS-Word may propose. After decades of combat with MS-Word, I have learned that Microsoft is more than a little "soft" when it comes to spelling and grammar . . .