When something is foggy, it's covered or filled with fog, that thick gray cloud that hangs close to the ground and makes it hard to see very far. On a foggy morning, you might not be able to see across the street, and car headlights glow softly through the mist. Ships use foghorns to warn each other when it's foggy at sea, since visibility drops to almost nothing.

The word also describes unclear thinking or memory. When you first wake up, your mind might feel foggy, like you can't quite think straight yet. If you try to remember something from long ago, the details might be foggy, meaning blurry or incomplete. A student who's tired during class might find that everything the teacher says sounds foggy, as if they can't quite focus or understand.

Things can also look foggy: a steamed-up bathroom mirror gets foggy after a hot shower, and your glasses might fog up when you come inside from the cold. In each case, whether it's weather, memory, or vision, foggy means unclear, obscured, or hard to see through.