Definitions of summit:

• noun:   a meeting of heads of governments
• noun:   the top point of a mountain or hill

  Example: "They clambered to the summit of Monadnock"

• noun:   the highest level or degree attainable

  Example: "The summit of his ambition"

• verb:   reach the summit of a mountain

  Example: "Many mountaineers go up Mt. Everest but not all summit"