You may wonder what happens behind the scenes whenever you do a spell check in PowerPoint or any other Microsoft Office program. This is what happens: PowerPoint looks at each word you have typed and matches those words with the entries listed within its dictionary. If the dictionary does not contain some of the words in your slides, it goes ahead and marks those words as misspelled. Then it offers you suggestions for changing those supposedly misspelled words to other similar words that can be found within its dictionary.
So why did we use the term “supposedly” in the last paragraph? That’s because PowerPoint’s dictionary is quite basic, and includes mainly words used in common, everyday language — if a word does not exist within that dictionary, it is not necessarily misspelled! There are so many specialized words in different knowledge branches like medicine, research, law, computing, etc. that are not common words — yet they are perfectly valid as far as spellings are concerned.
Learn how to load and use custom dictionaries in PowerPoint 2010 for Windows.

