To flinch means to make a sudden, involuntary movement away from something that startles or threatens you. When a doctor raises a needle for a shot, you might flinch even though you're trying to hold still. When someone pretends to throw a ball at your face, that automatic jerk backward is a flinch.

Flinching is your body's quick defense system reacting before your mind can think it through. It's why you might flinch at a loud bang, or pull your hand back when you almost touch a hot stove. Even when you know something won't actually hurt you, like a bug flying near your face, you might still flinch instinctively.

The word also describes backing away from difficult situations. If someone flinches from a challenge, they avoid it or show hesitation when they should push forward. A soccer goalie who doesn't flinch when a ball rockets toward them shows real courage, staying focused despite the instinct to duck.

Some people say “without flinching” to describe someone facing something difficult with steady determination. A student who presents their project to the class without flinching, even when nervous, shows confidence and resolve.