Office can automatically check spelling while you type and underline possible misspelled words with a red wavy line.
Choose Tools - Automatic Spell Checking.
Right-click a word with a red wavy underline, and then choose a suggested replacement word from the list, or from the AutoCorrect sub-menu.
If you choose a word from the AutoCorrect submenu, the underlined word and the replacement word are automatically added to the AutoCorrect list for the current language. To view the AutoCorrect list, choose Tools - AutoCorrect - AutoCorrect Options, and then click the Replace tab.
You can also add the underlined word to your custom dictionary by choosing Add.
Select the words that you want to exclude.
Click the Language control on the Status bar to open a menu.
Choose "None (Do not check spelling)".