A measure of the ease with which water penetrates a material.
The permeability of soil describes how water (or other liquid) and air are able to move through the soil. In the case of rainfall or irrigation, water moves very easily through highly permeable soils and very slowly through soils with low permeability.
Notice how water moves through the sand about 5 times faster than clay
EXAMPLE:
Another example of water flowing through gravel at the left verses clay at the right.
