Definition of peak:
the most extreme possible amount or value; "voltage peak"
the period of greatest prosperity or productivity
the highest level or degree attainable; the highest stage of development; "his landscapes were deemed the acme of beauty"; "the artist's gifts are at their acme"; "at the height of her career"; "the peak of perfection"; "summer was at its peak"; "...catapulted Einstein to the pinnacle of fame"; "the summit of his ambition"; "so many highest superlatives achieved by man"; "at the top of his profession"
the top or extreme point of something (usually a mountain or hill); "the view from the peak was magnificent"; "they clambered to the tip of Monadnock"; "the region is a few molecules wide at the summit"
a V shape; "the cannibal's teeth were filed to sharp points"
the highest point (of something); "at the peak of the pyramid"
a brim that projects to the front to shade the eyes; "he pulled down the bill of his cap and trudged ahead"
to reach the highest point; attain maximum intensity, activity; "That wild, speculative spirit peaked in 1929";"Bids for the painting topped out at $50 million"