A coaster is a small mat or pad you place under a cold drink to protect furniture from water rings and moisture. When ice makes your glass sweaty with condensation, the coaster catches those drips before they can damage a wooden table or leave marks on other surfaces.

Coasters come in many materials: cork, wood, ceramic, or even stone. Some families use simple cardboard coasters, while others collect decorative ones from different places they've visited. You'll find coasters in homes, restaurants, and anywhere people care about keeping their furniture looking nice.

The word also refers to a type of ship called a coastal trader, or coaster, which carries cargo along coastlines rather than crossing oceans. These smaller vessels move goods between nearby ports, sailing close to shore.

And then there's the most exciting kind: a roller coaster, the thrilling amusement park ride with steep drops and sharp turns. When you're on a roller coaster, you're coasting through those wild loops and dips, powered mostly by gravity and momentum after that first big climb.