What term describes a fabric treatment that adds weight without compromising flexibility?

The term that best describes a fabric treatment that adds weight without compromising flexibility is sizing. Sizing involves applying a substance to the fabric that enhances its body and weight, making it feel heavier while still allowing for flexibility and movement. This treatment is commonly used to improve the fabric's performance characteristics, such as its drape and texture, without creating stiffness or rigidity.

Sizing is often used in various fabric types to ensure that they retain their desired qualities during wear and handling. This technique is particularly important in apparel and accessories marketing, as it allows manufacturers to create products that meet consumer preferences for comfort and style.

The other options, while related to textile treatments, do not accurately capture the definition provided. Finishing refers to a broader range of treatments applied to fabric to enhance its appearance and performance. Coating typically involves applying a layer of substance that can alter the fabric's characteristics significantly, often leading to reduced breathability or flexibility. Bonding usually refers to joining two or more layers of fabric together, which can compromise flexibility depending on the materials used.