What is immiscibility?

Immiscibility (pronounced im-iss-ib-il-ity) is when you try to mix two liquids together but they separate instead. When this happens, we say that these liquids are immiscible. Water and oil are immiscible. Which is why, water will sink to the bottom (it is more dense) and oil will float to the top (it is less dense) instead of the 2 mixing.