What is the definition of 'hydrophilic'?

The term 'hydrophilic' describes substances that have an affinity for water and can interact favorably with it. This characteristic means that hydrophilic molecules or materials tend to dissolve in or mix well with water. The presence of polar groups within hydrophilic substances, such as hydroxyl (-OH) or carboxyl (-COOH) groups, allows them to form hydrogen bonds with water molecules. Because of this interaction, hydrophilic substances are often considered "water loving," making them important in various biological and chemical processes where water is a solvent.

The other definitions in the options do not capture the essence of hydrophilicity. For instance, 'water resisting', 'oil loving', and 'repels water' refer to characteristics of hydrophobic or non-polar substances, which do not interact well with water at all. These distinctions highlight how hydrophilic substances contrast sharply with hydrophobic ones, reinforcing the meaning behind 'water loving'.