Which of the following does not belong to the group of units of weight?

The term "heavy" does not belong to the group of units of weight because it is an adjective used to describe the mass or weight of an object rather than a specific unit of measurement. Units of weight such as kilogram, gram, and pound quantify the amount of matter in an object, allowing for precise measurement and comparison.

Units of weight like the kilogram, gram, and pound all provide a way to quantify how heavy an object is, making them essential in scientific and practical applications. "Heavy," however, is a qualitative description and does not offer a specific measurement. Therefore, it is categorized differently than the other options, which are all standardized units used to measure weight.