Force means strength or power used to make something happen or to make something move. When you push open a heavy door, you're using force. When wind blows hard enough to knock over a trash can, that's force too.

In science, force has a specific meaning: it's any push or pull that can change how an object moves. Gravity is a force that pulls objects toward Earth. Friction is a force that slows things down when they rub against each other. When you kick a soccer ball, the force from your foot sends it flying across the field. Isaac Newton discovered that force equals mass times acceleration, written as F = ma, which helps scientists predict exactly how objects will move.

The word also describes power used to make someone do something against their will. If someone tries to force you to hand over your lunch money, they're using threats or physical power unfairly. Police officers sometimes must use force to stop criminals, but they're trained to use only as much as necessary.

You can also force something open, like prying open a stuck window, or force yourself to finish homework when you'd rather play outside. When something happens by force, it means power or strength made it happen, not choice or agreement.

Related words include forceful (strong and powerful) and enforce (to make sure rules are followed).