cloth, fabric, textile, material - artifact made by weaving or felting or knitting or crocheting natural or synthetic fibers; "the fabric in the curtains was light and semitraqnsparent"; "woven cloth originated in Mesopotamia around 5000 BC"; "she measured off enough material for a dress"

stiffen - make stiff or stiffer; "Stiffen the cream by adding gelatine"

formal - being in accord with established forms and conventions and requirements (as e.g. of formal dress); "pay one's formal respects"; "formal dress"; "a formal ball"; "the requirement was only formal and often ignored"; "a formal education"