base | The expression that is being raised to a power when using exponential notation. In 5 a is the base. |

exponent | When a number is expressed in the form is the exponent. The exponent indicates how many times the base is used as a factor. Power and exponent mean the same thing.^{b} |

exponential decay | An exponential function of the form b < 1. The function decreases as x increases. |

exponential function | A function of the form b > 0 and b ≠ 1. |

exponential growth | An exponential function of the form b > 1, and b ≠ 1. The function increases as x increases. |

half-life | The amount of time it takes a substance to decrease to half its original amount. |

principal | In finance, the amount of money on which interest is calculated. |