To dissolve means to mix a solid substance into a liquid until it disappears and becomes part of the liquid. When you stir sugar into lemonade, the sugar crystals break apart into tiny pieces so small you can't see them anymore. The sugar hasn't vanished: it's still there, making your drink sweet, but it's now spread evenly throughout the liquid.

Different substances dissolve at different rates. Salt dissolves quickly in warm water but more slowly in cold water. Some things, like sand or oil, won't dissolve in water at all, no matter how long you stir. Scientists call a substance that dissolves well in a liquid soluble, while substances that won't dissolve are insoluble.

The word also means to end or break up something officially. When a partnership dissolves, the people involved decide to go their separate ways. If a student council dissolves a committee, that group stops existing. You might read about a country dissolving its parliament, meaning that governing body has been formally ended. In old movies, a scene might dissolve into the next one, with the first image gradually fading away as the new image appears.