If you are asking on how to activate in MS Word it is either key F7 or tools - spell checker.
Review Tab Proofing Group
Yes, spell checkers can distinguish between homonyms based on context. By analyzing the surrounding words in a sentence, spell checkers can suggest the correct spelling of a homonym to ensure the intended meaning is conveyed accurately.
Generally, a spell checker will not correct words that are misspelled in context. A grammar checker might catch 'there' vs. 'they're' - but since both are words, a spell checker wouldn't care.
You can download a spell checker from a variety of online sites. The best way to find them is by doing a search using the keywords spell checker.
There is no spell checker on Answers.
Excel has a spell checker. If you go into the Tools menu there is a Spellchecker option there. You also can just press the F7 key to start it.
According to my spell checker, it's two words. Note: Do not rely on spell checkers. They are incompetent, every single one.
While there were attempts to create automated spell checkers as early as 1957, the first functional spell checker was created in February 1971 by Ralph Gorin, a Stanford graduate student. The spell checker was installed on a DEC PDP-10, located in Stanford University's Artificial Intelligence lab. The first patent to use a spell checker with a computer software program was issued to Software Concepts, Inc. in 1978. It is not clear which was the first application to use the spell checker, but photo-typesetting programs from Lanier, Philips, and Xerox included a spell checker.
A spell checker application.
spell checker
WikiAnswers now has a spell checker! When you click to answer a question, or edit an existing answer, there is a link both above and below the answer box that allows you to check your spelling!
Spell checker.