peak¹ / pēk/ • n. the pointed top of a mountain: the snowy peaks rose against the blue of a cloudless sky. ∎  a mountain, esp. one with a pointed top: the rocky outcrops of peaks such as the Cassongrat offer a challenge to rock climbers. ∎  a projecting pointed part or shape: whisk 2 egg whites to stiff peaks. ∎  a point in a curve or on a graph, or a value of a physical quantity, higher than those around it: a slight increase in velocity provides a second peak on the general velocity curve. ∎  the point of highest activity, quality, or achievement: anyone who saw Jones at his peak looked upon genius. ∎  chiefly Brit. a stiff brim at the front of a cap. ∎  the narrow part of a ship's hold at the bow or stern. ∎  the upper, outer corner of a sail extended by a gaff.• v. [intr.] reach a highest point, either of a specified value or at a specified time: its popularity peaked in the 1940s the rate of increase peaked at 34 percent last autumn.• adj. greatest; maximum: he did not expect to be anywhere near peak fitness until Christmas. ∎  characterized by maximum activity or demand: at peak hours, traffic speeds are reduced considerably.DERIVATIVES: peak·y adj.peak·i·ness / -kēnis/ n.peak² • v. [intr.] archaic decline in health and spirits; waste away.

peak1 pointed extremity; projecting part of the brim of a cap XVI; pointed top of a mountain XVII. prob. back-formation from peaked, var. of (dial.) picked pointed, f. PICK1 + -ED2. In the earliest exx. of the last sense, rendering or repr. Sp., Pg. pico.

peak2 †fall, tumble; †shrink, slink, sneak XVI; look sickly or emaciated (p. and pine) XVII. of unkn. orig.