Wedge placed next to a wheel to prevent it from moving

CHOCK

This block is often used on airplanes or trailers to keep them securely in place.

The clue describes a "wedge placed next to a wheel to prevent it from moving," which directly points to a "chock," a common tool used to block wheels on vehicles or aircraft. There’s no wordplay here—it’s a straightforward definition where the answer fits the description exactly. If you’ve ever seen a wedge under a tire to keep it from rolling, that’s a chock. The word itself is simple and matches the clue without any hidden meanings.