The term 'Newton (Cookie)' is a reference to the FIG Newton, a type of cookie made by Nabisco. The FIG Newton is a pastry filled with FIG jam and covered in a thin layer of pastry dough. It was first created in 1891 and named after Sir Isaac Newton, an English physicist and mathematician. The crossword solution for this term is 'FIG, ' which is a three-letter word referring to the FIG filling inside the cookie.