The term 'used a hammer' can be summarized by two crossword solutions: 'nailed' and 'peened'. Nailing is the process of using a hammer to drive nails into a surface, while peening is the process of using a hammer to shape metal. Both processes involve striking an object with a hammer, but the end result is different. Nailing is used to join two objects together, while peening is used to shape metal into a desired shape.