Flannel or brushed cotton is a softly woven fabric, typically used for sleepwear and shirts. It can be of plain or twill weave, and the brushed surface can vary from being subtle to quite a thick pile. You may need to consider the pile when cutting out.
Flannel can come in a range of prints or checks and is typically made from cotton. It can also be used as an interlining for coats and jackets.