hydrophobic

Imagine oil and water—they just do not get along. That is the basic idea here. The term comes from "hydro" (water) and "phobic" (fearing), so it literally means "water-fearing." In real use, though, it is not about actual fear. It describes a substance or surface that repels water or does not mix with it easily. Think of a duck's feathers or a waxed car: water forms beads and rolls off. This idea matters in science and in daily life, from waterproof clothing to the outer parts of cell membranes. Sometimes people use the word in a creative or metaphorical way, but its main use is still in science.

"Hydrophobic" describes substances or surfaces that do not interact well with water. Instead of mixing with it, they tend to repel it. This is a basic idea in chemistry and biology, and it helps explain why some materials behave so differently from others. Oil, wax, and grease are common examples. When you mix them with water, they usually separate instead of dissolving.

This behavior comes from molecular structure. Many such substances are non-polar, which means their electrical charge is spread fairly evenly. Water is polar, so it is attracted to other polar substances more easily. A useful chemistry rule is "like dissolves like": water mixes well with substances that are similar to it, but not with non-polar ones.

This idea is also very important in biology. Cell membranes, for example, contain parts that repel water, helping the cell control what goes in and out. These interactions also help proteins fold into the right shape. In many scientific contexts, understanding this property helps explain how living systems stay organized.

The word is mainly scientific, though people sometimes use it in a loose, metaphorical way to suggest strong resistance or separation. Still, its true meaning is about the way water behaves around a material. So when you see rain bead up on a freshly waxed car or slide off a waterproof jacket, you are seeing this property in action.