wobbly

A wobbly thing is unstable or unsteady.

You might hear people say that their chair is wobbly if it keeps tipping over. This can happen with old furniture or anything made of flimsy materials. A wobbly bike wheel means the tire isn't properly attached, making it difficult to balance on the bike. If a bridge looks wobbly after an earthquake, it's probably not safe for people to walk on until it's fixed. In general, when something is described as wobbly, you can expect it to be prone to swaying or tilting in an unpredictable way.