The term 'Step Up or Down' is a phrase used to describe the action of climbing or descending stairs. The crossword solutions for this term are STAIR (5 letters) and RUNG (4 letters). Stairs are composed of steps, which are connected by a vertical structure called a riser. Each step is made up of a flat surface, known as a tread, and a vertical support, known as a RUNG. Together, these two components form a staircase, allowing people to move up or down between different levels of a building.