How is someone described as "emaciated"?

The term "emaciated" specifically refers to someone who is extremely thin or weakened, often as a result of malnutrition or illness. This condition typically implies that the person has lost a significant amount of weight, leading to a gaunt or skeletal appearance. It emphasizes an abnormal thinness that is concerning for health, rather than simply being of a lesser weight or having a different physique.

In contrast, the other descriptions do not align with this meaning. Being vigorously active and healthy suggests a strong, robust individual, while average weight indicates a typical and balanced body type. Noticeably muscular refers to a well-developed physique, which is the opposite of being emaciated. Therefore, the correct understanding of the term accurately captures the severity and implications of extreme thinness associated with "emaciated."