Source : Webster's Revised Unabridged Dictionary (1913)

Peak \Peak\, n. [OE. pek, AS. peac, perh of Celtic origin; cf.
   Ir. peac a sharp-pointed thing. Cf. {Pike}.]
   1. A point; the sharp end or top of anything that terminates
      in a point; as, the peak, or front, of a cap. ``Run your
      beard into a peak.'' --Beau. & Fl.

   2. The top, or one of the tops, of a hill, mountain, or
      range, ending in a point; often, the whole hill or
      mountain, esp. when isolated; as, the Peak of Teneriffe.

            Silent upon a peak in Darien.         --Keats.

   3. (Naut.)
      (a) The upper aftermost corner of a fore-and-aft sail; --
          used in many combinations; as, peak-halyards,
          peak-brails, etc.
      (b) The narrow part of a vessel's bow, or the hold within
          it.
      (c) The extremity of an anchor fluke; the bill. [In the
          last sense written also {pea} and {pee}.]

   {Fore peak}. (Naut.) See under {Fore}.

Peak \Peak\, v. i. [imp. & p. p. {Peaked}; p. pr. & vb. n.
   {Peaking}.]
   1. To rise or extend into a peak or point; to form, or appear
      as, a peak.

            There peaketh up a mighty high mount. --Holand.

   2. To acquire sharpness of figure or features; hence, to look
      thin or sicky. ``Dwindle, peak, and pine.'' --Shak.

   3. [Cf. {Peek}.] To pry; to peep slyly. --Shak.

   {Peak arch} (Arch.), a pointed or Gothic arch.

Peak \Peak\, v. t. (Naut.)
   To raise to a position perpendicular, or more nearly so; as,
   to peak oars, to hold them upright; to peak a gaff or yard,
   to set it nearer the perpendicular.

Source : WordNet®

peak
     adj 1: of a period of maximal use or demand or activity; "at peak
            hours the streets traffic is unbelievable" [ant: {off-peak}]
     2: approaching or constituting a maximum; "maximal
        temperature"; "maximum speed"; "working at peak
        efficiency" [syn: {highest}, {peak(a)}]

peak
     n 1: the most extreme possible amount or value; "voltage peak"
          [syn: {extremum}]
     2: the period of greatest prosperity or productivity [syn: {flower},
         {prime}, {heyday}, {bloom}, {blossom}, {efflorescence}, {flush}]
     3: the highest level or degree attainable; "his landscapes were
        deemed the acme of beauty"; "the artist's gifts are at
        their acme"; "at the height of her career"; "the peak of
        perfection"; "summer was at its peak"; "...catapulted
        Einstein to the pinnacle of fame"; "the summit of his
        ambition"; "so many highest superlatives achieved by man";
        "at the top of his profession" [syn: {acme}, {height}, {elevation},
         {pinnacle}, {summit}, {superlative}, {top}]
     4: the top point of a mountain or hill; "the view from the peak
        was magnificent"; "they clambered to the summit of
        Monadnock" [syn: {crown}, {crest}, {top}, {tip}, {summit}]
     5: a V shape; "the cannibal's teeth were filed to sharp points"
        [syn: {point}, {tip}]
     6: the highest point (of something); "at the peak of the
        pyramid" [syn: {vertex}, {apex}, {acme}]
     7: a brim that projects to the front to shade the eyes; "he
        pulled down the bill of his cap and trudged ahead" [syn: {bill},
         {eyeshade}, {visor}, {vizor}]

peak
     v : to reach the highest point; attain maximum intensity,
         activity; "That wild, speculative spirit peaked in 1929"