What do you call furniture that is made and finished specifically for outdoor use?

Furniture made and finished specifically for outdoor use is called patio furniture.

Patio furniture is also commonly called outdoor furniture or garden furniture. It includes tables, chairs, benches, loungers, umbrellas, and other pieces designed for patios, decks, balconies, gardens, and terraces. A typical patio set may include a table, four or six chairs, and a parasol or umbrella.

Because outdoor furniture is exposed to rain, sunlight, humidity, and temperature changes, manufacturers commonly use weather-resistant materials. Aluminum, treated wood, teak, plastic, synthetic resin, wicker, rattan, rope, and outdoor-rated fabrics are all widely used.

The term “patio furniture” describes its intended setting rather than one particular material or style. A wooden chair can be patio furniture if it is treated for outdoor conditions, while an ordinary indoor chair may deteriorate quickly outside. Patio furniture is therefore defined mainly by its construction, finish, and resistance to weather.