Meaning of starch

(noun) a complex carbohydrate found chiefly in seeds, fruits, tubers, roots and stem pith of plants, notably in corn, potatoes, wheat, and rice; an important foodstuff and used otherwise especially in adhesives and as fillers and stiffeners for paper and textiles

a commercial preparation of starch that is used to stiffen textile fabrics in laundering

(verb) stiffen with starch; "starch clothes"