A mixture in which dispersed particles are too light to settle out is called a suspension.

Here's why:

* Suspensions are heterogeneous mixtures where the dispersed particles are larger than those in solutions (typically 100nm to 1 micrometer in size).

* Colloids are a type of suspension where the dispersed particles are small enough to remain suspended indefinitely, preventing them from settling.

Let me know if you'd like more detail on suspensions or colloids!