* Element: An element is a pure substance made up of only one type of atom (like oxygen or hydrogen). Distilled water contains two different elements.

* Compound: A compound is formed when two or more elements chemically combine in a fixed ratio. Water (H₂O) is formed by the chemical combination of hydrogen and oxygen.

* Heterogeneous mixture: A heterogeneous mixture has components that are visibly different and can be easily separated. Distilled water is uniform throughout.

* Solution: A solution is a homogeneous mixture where one substance (solute) dissolves completely into another (solvent). While distilled water is a solution, it's specifically the solution of water itself (H₂O).

* Colloid: A colloid is a mixture where particles are dispersed throughout a medium but are not fully dissolved. Distilled water doesn't have particles dispersed within it.

In short: Distilled water is a compound because it is made up of two elements (hydrogen and oxygen) chemically bonded together.