Natural:
* Skin: Think of a baby's bottom or a dolphin's back.
* Water: A still pond, a calm ocean.
* Rocks: Polished river stones, certain types of marble.
* Leaves: Some plants have smooth leaves, like those of a banana tree or a magnolia.
* Animal fur: Seals, otters, and some breeds of cats have very smooth fur.
* Seashells: Many seashells have a smooth, polished surface.
Man-Made:
* Glass: A window pane, a wine glass, a mirror.
* Metal: A polished silver tray, a smooth steel surface.
* Plastic: A smooth plastic toy, a glossy phone case.
* Fabric: Silk, satin, velvet, and some types of cotton can be very smooth.
* Paper: Glossy paper, a smooth surface for drawing or writing.
* Paint: A freshly painted wall, a smooth enamel surface.
* Ceramic: A glazed tile, a smooth porcelain cup.
* Leather: A well-maintained leather jacket, a polished leather shoe.
Abstract:
* Sound: A smooth transition between musical notes.
* Movement: A graceful dance, a smooth car ride.
* Language: A well-written sentence, a smooth and flowing speech.
Important Note: Smoothness is subjective. What one person finds smooth, another may find rough. The context and the way something feels also affect our perception of smoothness.