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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.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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.
Power producers cite need for more peaking plants !-- -- Danessa Rivera (The Philippine Star) - April 28, 2019 - 12:00am MANILA, Philippines The country needs to develop more peaking power plants or those plants that can run during peak hours in order to address any sudden spikes in demand and address the problem of brownouts, according to the country's power producers.