You’ve been saying it in the wrong context forever and now it’s time to stop.

5.

What you think it means: Very quick growth.
What it actually means: An increase in the rate of growth. Something is growing exponentially when its rate of change can be described using an exponent, such as 103.

6.

What you think it means: Something that’s very big.
What it actually means: The extreme scale, seriousness, or extent of something that’s bad or morally wrong. Can also mean a grave crime or sin. As in: “We only just discovered the enormity of the crimes he committed.”