Definition: From the Greek (hydros) "water" and (philia) "friendship", a molecule that is hydrophillic is "friendly" with water - meaning that it can bond with (and dissolve in) a water molecule.
Soap molecules have one side that is hydrophilic and one side that is hydrophobic which allows it to bond with, and dissolve in, both water and oils - which is why soap helps the water clean better.
