noun

• (geography) The top, or one of the tops, of a hill, mountain, or range, ending in a point.
  "They reached the peak after 8 hours of climbing."
• (geography) The whole hill or mountain, especially when isolated.
  "To the South we observed a large plain some ten miles wide, with snowy peaks rising on the farther side. In front was a hill projecting into the plain, on which stood a mani wall; and this latter discovery made me feel quite confident that I was on the high road to Lhassa."
• (clothing, UK) visor (horizontal part of a cap sticking out in front and shading the wearer's eyes)
• (nautical) The upper aftermost corner of a fore-and-aft sail.
  "peak-halyards"

verb

• (transitive, nautical) To raise the point of (a gaff) closer to perpendicular.
• (transitive, signal processing) To exceed the maximum signal amplitude of (a piece of equipment), resulting in clipping of the signal.
  ""Dr. Reynders?" Udo prodded."
• (intransitive)
  "Historians argue about when the Roman Empire began to peak and ultimately decay."
• (intransitive)
  "There peaketh up a mightie high mounte."

adj

• (slang) Maximal, quintessential, archetypical, strictly with positive connotations; representing the culmination of its type.
  "Knowing obscure 19th-century slang is peak nerd."
• (MLE) Bad.
  "When they're tryna get the girl to the crib and she leaves, it's peak / Tryna keep it discreet and she tweets, it's peak / See me rolling with 20 man deep, it's peak / Yo rudeboy, pull up, repeat, it's peak"
• (MLE) Unlucky; unfortunate.
  "You didn't get a spot? That's peak."
• (Internet slang) Very good or high-quality.
  "That movie last night was so peak."

verb

• (intransitive) To become sick or wan.
• (intransitive) To acquire sharpness of figure or features; hence, to look thin or sickly.
  "Dwindle, peak, and pine."
• (intransitive) To pry; to peep slyly.