Definitions of peak:

• noun:   the top point of a mountain or hill

  Example: "The view from the peak was magnificent"

• noun:   a brim that projects to the front to shade the eyes
• noun:   the highest point (of something)

  Example: "At the peak of the pyramid"

• noun:   the most extreme possible amount or value

  Example: "Voltage peak"

• noun:   a V shape
• noun:   the period of greatest prosperity or productivity
• noun:   the highest level or degree attainable

  Example: "The peak of perfection"

• verb:   to reach the highest point; attain maximum intensity, activity

  Example: "That wild, speculative spirit peaked in 1929"

• adjective:   of a period of maximal use or demand or activity

  Example: "At peak hours the streets traffic is unbelievable"

• name:  A surname (rare: 1 in 25000 families; popularity rank in the U.S.: #3004)