Final answer:
The projections from the small intestine's lining that help in nutrient absorption are called villi, which further possess microvilli to enhance their absorptive capacity.
Step-by-step explanation:
The multicelled projections that protrude from the lining of the small intestine to aid in the absorption of nutrients are called villi. These villi create a large surface area which is further increased by substructures known as microvilli. The inner surface of the small intestine is greatly enlarged by the presence of circular folds, villi, and microvilli, which allow for efficient absorption of nutrients from the passing chyme. Specifically, the microvilli are lined with blood vessels and lymphatic vessels, helping in the transport of absorbed nutrients.