Source: http://mentalfloss.com
HEARTBURN
Used to mean: Jealousy or hatred
"Heartburn" hasn't ever actually involved the heart. It once referred to feelings that come from the mind. Now it describes an issue with your stomach or esophagus.
INMATE
Used to mean: A tenant or housemate
Try posting an "Inmate Wanted" ad on Craigslist today and see what happens.
BULLY
Used to mean: Superb, wonderful
When Theodore Roosevelt referred to the presidency as a bully pulpit, he wasn't talking about name-calling, harassment, or beating anyone with a big stick. He was praising the social change he might shape in office. Bully for him!
ARTIFICIAL
Used to mean: Full of artistic and technical skill
Think about it: It takes a lot of skill to reproduce a flower in silk or realistic-feeling latex.
AWFUL
Used to mean: Commanding awe
Here's an awfully good example from Moby Dick: "There is, one knows not what sweet mystery about this sea, whose gently awful stirrings seems to speak of some hidden soul beneath..."
