Why does ice make drinks colder without diluting them immediately?

Ice cools drinks through heat transfer: the drink's thermal energy flows into the ice, lowering the liquid's temperature. The key is that melting ice requires a large amount of energy called latent heat of fusion. Ice must absorb about 334 joules per gram just to change from solid to liquid, without its temperature rising during that phase change. This means the ice spends a lot of time absorbing heat before it actually melts into water. So in the early stages, the ice is pulling heat out of the drink and converting from solid to liquid slowly, chilling the beverage significantly before much liquid water is added. Dilution becomes noticeable only after substantial melting has occurred, which takes time depending on the drink's temperature and the ice's surface area.