n. & v.
n. 1 a projecting usu. pointed part, esp.: a the pointed top of a mountain. b a mountain with a peak. c a stiff brim at the front of a cap. d a pointed beard. e the narrow part of a ship's hold at the bow or stern (forepeak; after-peak). f Naut. the upper outer corner of a sail extended by a gaff. 2 a the highest point in a curve (on the peak of the wave). b the time of greatest success (in a career etc.). c the highest point on a graph etc.
v.intr. reach the highest value, quality, etc. (output peaked in September). peak hour the time of the most intense traffic etc. peak-load the maximum of electric power demand etc. peaked adj. peaky adj. peakiness n.
[ prob. back-form. f. peaked var. of dial. picked pointed (PICK(2)) ]