What term describes substances that have an affinity for water?

The term that describes substances with an affinity for water is "hydrophilic." Hydrophilic substances are characterized by their ability to interact and form hydrogen bonds with water molecules, thus making them soluble in water or able to disperse readily in aqueous environments. This affinity arises from their polar or charged nature, which allows them to interact effectively with water, a polar solvent.

In contrast, hydrophobic substances are those that do not mix well with water; they are repelled by water molecules and typically consist of nonpolar molecules. The term "amphipathic" refers to molecules that have both hydrophilic and hydrophobic regions, which can interact with both water and lipids, making them important in the structure of cell membranes. Nonpolar substances generally do not have an affinity for water and do not dissolve in it, further distinguishing them from hydrophilic substances.