impermeable

Imagine trying to build a sandcastle during high tide. If your walls are impermeable and water cannot get through them, you might just succeed. The word comes from Latin roots that suggest the idea of not letting something pass through.

Something impermeable acts as a barrier against liquid, gas, or moisture. A good raincoat may be made of impermeable material, keeping you dry in the rain. The word can also be used in a figurative way. You might say someone seems impermeable to advice or criticism if those things do not get through to them.

The word impermeable describes something that does not let liquid or gas pass through it. Think of a tightly sealed container, a layer of rock, or a well-made rain jacket. If it is impermeable, it forms a barrier that keeps water, air, or other substances from moving through.

You will often see impermeable in science and engineering. Geologists talk about impermeable rock layers that stop groundwater from flowing through them. Engineers use impermeable membranes and barriers in construction, packaging, and water systems. In everyday life, you might describe a high-quality rain jacket or pair of boots as impermeable if they keep moisture out.

But the word is not limited to physical things. It can also be used metaphorically to describe a person who does not respond to ideas, feelings, or influence. If someone is impermeable to reason, they do not listen to logic. If a character seems impermeable to sympathy, they are untouched by it.

So whether it describes a material that keeps out water or a person who shuts out influence, impermeable suggests that something cannot easily get through.