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This word gets tossed around frequently, but not always correctly. We may hear that a new trend is "growing exponentially," or that a booming industry is experiencing "exponential growth," or even that one thing is "exponentially better" than another.

In everyday use, exponential has come to mean extremely large or rapid, but mathematically speaking, exponential growth simply means that something is growing at a rate proportional to its size. The rate of growth may be large or small. So if our economy grows at 0.1 percent a year, that's exponential growth, but it's hardly impressive [source: Safire].

Another common misconception is that if something is growing exponentially, it must be increasing by powers of 2, 3 and so on. If we hear that Earth's population is increasing exponentially, we may be horrified at the thought of 49 quintillion people suddenly fighting for resources. But exponential population growth means that the change in population over a given period of time is proportional to the population size. Right now that rate of growth is estimated to be around 1 percent per year, which works out to 70 million additional people [source: Annenberg].

The next scientific term on our list also relates to size. Leap to the next page to read more.