Other forms: rungs
A rung is one of the horizontal steps of a ladder. You should never stand on the very top rung of a ladder — it can be dangerous!
From the literal ladder definition of rung, a place to put your foot (or hand) as you climb up, comes the metaphorical meaning of "a level." For example, if you get a promotion at work, you might say you're climbing up the rungs of the company. The horizontal bars between the legs of a chair are also rungs. This word comes from a Germanic root meaning "stake, staff, or bar."