A shortfall is the gap between what you need or expect and what you actually have. When there's a shortfall, you're coming up short: you don't have quite enough of something.

If your class needs to raise $500 for a field trip but only collects $425, there's a $75 shortfall. If a baker expects to sell 100 cupcakes but only has ingredients for 85, she faces a shortfall of 15 cupcakes. If a basketball team hoped to win 20 games this season but only won 14, they experienced a shortfall in wins.

The word usually applies to measurable things: money, supplies, points, or time. A school district facing a budget shortfall doesn't have enough money to cover its planned expenses. A charity experiencing a donation shortfall received fewer contributions than it needed.

Notice that shortfall describes the missing amount specifically. If you studied for two hours instead of your planned three hours, there's a one-hour shortfall in your study time. The word helps us identify exactly how much more we need, which is the first step in figuring out how to make up the difference.