What term describes three or more monosaccharides linked together?

The term that describes three or more monosaccharides linked together is "polysaccharide." Polysaccharides are complex carbohydrates formed by the polymerization of monosaccharide units, which are simple sugars. These compounds can be quite large and include a variety of structures and functions, such as energy storage (like starch in plants and glycogen in animals) and structural components (like cellulose in plant cell walls).

In contrast, disaccharides consist of only two monosaccharide units linked together, while oligosaccharides typically refer to short chains of monosaccharides, usually containing 2 to 10 units. A tri-saccharide, while it indicates three sugar units, is a specific case within the broader category of polysaccharides. Hence, the broader term that encompasses three or more monosaccharides is polysaccharide, making it the correct choice in this context.