Extracted from study.com/academy
The word hydrophobic comes from the Greek roots hydro- (meaning water) and -phobia (meaning fearing or hating). The word hydrophobic describes the fact that non-polar substances will not combine with water molecules.
Water is a polar molecule, which means that it carries a partial charge between its atoms. Oxygen, as an electronegative atom, draws the electrons of each bond closer to its core, thus creating a more negative charge. Therefore, any materials with either a negative or positive charge, will be able to interact with water molecules to dissolve.
So essentially, hydrophobic molecules are molecules that do not have a charge, meaning they are non-polar. By lacking a charge, these molecules do not have any charge-to-charge interactions that will allow them to interact with water. Hydrophobic materials often do not dissolve in water or in any solution that contains a largely aqueous (watery) environment.
This characteristic of being hydrophobic - or non-polar - is important for many of the molecules found in nature, in other organisms, and even within our own bodies.
Waxes are practical examples of hydrophobic molecules that are used commercially and biologically because of their abilities to resist interacting with water. For example, if you have ever had your car waxed, you probably noticed that the water would bead up and roll off of the paint afterwards. This is because the applied wax is hydrophobic and will not interact with water. Waxes, in this case, help to keep water away from the surface of the car.
