Water fearing, from the Greek words hydro - "water" and phobo - "fear." The hydrophobic effect is the entropy driven force that causes oil to separate from water. It is notoriously strong, though not as strong as covalent forces. This force is one of the main determinants of the structure of globular protein molecues, since the hydrophilic (water loving) parts of the molecule tend to surround the hydrophobic parts that cluster in the center, away from the aqueous (polar) solvent.