Also found in: Thesaurus, Medical, Legal, Financial, Encyclopedia, Wikipedia.

peak 1

1. A tapering, projecting point; a pointed extremity: the peak of a cap; the peak of a roof.
a. The pointed summit of a mountain.
b. The mountain itself.
a. The point of a beard.
b. A widow's peak.
4. The point of greatest development, value, or intensity: a novel written at the peak of the writer's career. See Synonyms at summit.
5. Physics The highest value attained by a varying quantity: a peak in current.
6. Nautical
a. The narrow portion of a ship's hull at the bow or stern.
b. The upper aft corner of a quadrilateral fore-and-aft sail.
c. The outermost end of a gaff.
v. peaked, peak·ing, peaks
1. Nautical To raise (a gaff) above the horizontal.
2. To bring to a maximum of development, value, or intensity.
1. To be formed into a peak or peaks: Beat the egg whites until they peak.
2. To achieve a maximum of development, value, or intensity: Sales tend to peak just before the holidays.
Approaching or constituting the maximum: working at peak efficiency.

[Probably Middle English pike, peke; see pike5.]

peak 2

intr.v. peaked, peak·ing, peaks Archaic
To become sickly, emaciated, or pale.

[Origin unknown.]
References in classic literature ?
First, when used as a fin for progression; Second, when used as a mace in battle; Third, in sweeping; Fourth, in lobtailing; Fifth, in peaking flukes.
Excepting the sublime breach --somewhere else to be described --this peaking of the whale's flukes is perhaps the grandest sight to be seen in all animated nature.
Even if we prepare ourselves for the peaking of oil production with a sensible, broad-based energy plan, we'll still be faced with the pain of prices marching relentlessly higher for years to come in order to match demand to steadily diminishing supplies.