William Safire, in his weekly “On Language” column in the New York Times Magazine, writes about the origins of the word “good,” in an effort to explain its common contemporary usage in the phrase “I’m good,” which usually means something along the lines of “I’m Okay,” or “I’ve had enough,” or “I can handle it.” Safire explains:

Here we have one of the basic words of the English language–originally used in the place of God to avoid irreverance–gaining currency in an unremarked new sense. Early on, I’m good meant “I am without sin,” but that is now seldom the meaning.”

So the word “good” was originally “God” plus an extra “O.” Who knew?