Peak (noun)

1. The highest point of something, especially a mountain.
2. The most successful or advanced point in the development or progress of something.
3. The highest or maximum level or amount of something, especially of production, demand, or activity.
4. The pointed top of a hat.

Origin:

Late middle english from old norse pik meaning point, peak.

Examples:

1. Mount Everest is the highest peak in the world.
2. The company's sales reached its peak in the year 2000.
3. The demand for oil is at its peak during the summer months.
4. He wore a black suit and a red peaked cap.
5. The peak of the recession was in 2009.