The blow dryer attachment that spreads airflow gently over a larger area is called a:

A diffuser is specifically designed to spread airflow gently over a larger area, making it particularly beneficial for drying curly or wavy hair without causing frizz. It works by dispersing the air from the blow dryer, allowing for a more even and subtle drying process. This gentle airflow helps to maintain the natural texture of the hair, reducing the risk of heat damage and promoting a softer, more defined curl or wave.

The other attachments serve different functions. A concentrator narrows the airflow, directing it to a specific area for more focused drying or styling, making it ideal for straightening or smoothing out sections of hair. A comb attachment is used to straighten hair while drying, often making the process quicker but not suitable for enhancing curls. A deflector, while sometimes used in hair styling, is not a standard term associated with blow dryer attachments in this context.