Awe, Awful and Awesome
Have you ever wondered about these words? How is it that if something is awful - full of 'awe' - then it is terrible, but if something is 'awesome' - having some 'awe' - then it is great?
In fact, awful is closer to the original definition. Both words share the root word 'awe', which meant 'fear and terror'. Over time, influenced by biblical texts, 'awe' came to mean 'reverential fear' as in 'the fear of God' and then later took the meaning that we associate with it today - a sense of wonder or shock. It still retains something of its old meaning; American bombing campaigns in Iraq were said to cause 'shock and awe'.
So hundreds of years ago, awful and awesome meant the same thing. As the use of the root word awe changed, awesome came to mean excellent, while awful retained the original meaning.
It's another example of how a word can eventually come to mean the opposite.