`water-loving', typically polar molecules or parts of molecules
are hydrophilic as they are attracted to water molecules which are
polar. Compare hydrophobic.
The actual nature of the repulsive is very complex.
It can be naively understood as the cumulative effect of effect of
electrostatic, hydration and steric interactions.
`water-hating', typically non-polar molecules or parts of molecules
are hydrophobic as they are not attracted to water molecules which are
polar. Compare hydrophilic.