A multiplier is a number that you multiply another number by. In the multiplication problem 6 × 4 = 24, the 6 is the multiplier (and the 4 is called the multiplicand). When you think “I want four groups of six things,” the four is your multiplier because it tells you how many times to use the six.

The word also describes something that increases or amplifies an effect. In economics, a spending multiplier means that when one person spends money, it creates jobs and income for others, who then spend their money, creating a ripple effect that multiplies the original impact. If someone donates $10 to a food bank, and that helps feed someone who then has energy to work and earn money to help their own family, that donation had a multiplier effect.

In video games, a score multiplier increases your points. Getting a 2× multiplier means every point you earn counts as two. Athletes sometimes use the term too: lifting weights can have a multiplier effect on your strength because stronger muscles help you perform better in many different activities, not just weightlifting.

The key idea is that a multiplier takes something and makes it bigger, whether that's a number in math class or an effect spreading through a system.