What lightweight fabric, often featuring a small floral design, is commonly used for pajamas and dresses?

Challis is indeed the lightweight fabric commonly associated with pajamas and dresses, particularly those that feature small floral designs. This fabric is known for its soft and smooth texture, making it comfortable against the skin, which is especially desirable for sleepwear and casual dresses. Its lightweight nature also contributes to its drapability, allowing garments made from challis to have a flowy, relaxed fit that is ideal for loungewear and summer outfits.

In contrast, cotton lawn, while also lightweight and smooth, tends to be slightly crisper and may not be as commonly used for pajamas as challis. Georgette is a semi-sheer fabric that is often used for more formal garments and dresses but is not typically associated with the casual and comfortable feel of pajamas. Pique, on the other hand, is a fabric characterized by a raised texture that is frequently used in sportswear and polo shirts rather than for lightweight, floral-patterned dresses. Thus, challis stands out as the most appropriate choice for the context of the question.