The Collaborative International Dictionary of English v.0.48:

Curl \Curl\, v. i.
   1. To contract or bend into curls or ringlets, as hair; to
      grow in curls or spirals, as a vine; to be crinkled or
      contorted; to have a curly appearance; as, leaves lie
      curled on the ground.
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            Thou seest it [hair] will not curl by nature.
                                                  --Shak.
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   2. To move in curves, spirals, or undulations; to contract in
      curving outlines; to bend in a curved form; to make a curl
      or curls. "Cirling billows." --Dryden.
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            Then round her slender waist he curled. --Dryden.
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            Curling smokes from village tops are seen. --Pope.
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            Gayly curl the waves before each dashing prow.
                                                  --Byron.
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            He smiled a king of sickly smile, and curled up on
            the floor.                            --Bret Harte.
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   3. To play at the game called curling. [Scot.]
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The Collaborative International Dictionary of English v.0.48:

Curl \Curl\ (k[^u]rl), v. t. [imp. & p. p. Curled (k[^u]rld);
   p. pr. & vb. n. Curling.] [Akin to D. krullen, Dan.
   kr["o]lle, dial. Sw. krulla to curl, crisp; possibly akin to
   E. crook. Cf. Curl, n., Cruller.]
   1. To twist or form into ringlets; to crisp, as the hair.
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            But curl their locks with bodkins and with braid.
                                                  --Cascoigne.
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   2. To twist or make onto coils, as a serpent's body.
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            Of his tortuous train,
            Curled many a wanton wreath in sight of Eve.
                                                  --Milton.
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   3. To deck with, or as with, curls; to ornament.
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            Thicker than the snaky locks
            That curledMeg[ae]ra.                 --Milton.
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            Curling with metaphors a plain intention. --Herbert.
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   4. To raise in waves or undulations; to ripple.
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            Seas would be pools without the brushing air
            To curl the waves.                    --Dryden.
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   5. (Hat Making) To shape (the brim) into a curve.
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The Collaborative International Dictionary of English v.0.48:

Curl \Curl\ (k[^u]rl), n. [Akin to D. krul, Dan. kr["o]lle. See
   Curl, v. ]
   1. A ringlet, especially of hair; anything of a spiral or
      winding form.
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            Under a coronet, his flowing hair
            In curls on either cheek played.      --Milton.
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   2. An undulating or waving line or streak in any substance,
      as wood, glass, etc.; flexure; sinuosity.
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            If the glass of the prisms . . . be without those
            numberless waves or curls which usually arise from
            the sand holes.                       --Sir I.
                                                  Newton.
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   3. A disease in potatoes, in which the leaves, at their first
      appearance, seem curled and shrunken.
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   Blue curls. (Bot.) See under Blue.
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WordNet (r) 3.0 (2006):

curl
    n 1: a round shape formed by a series of concentric circles (as
         formed by leaves or flower petals) [syn: coil, whorl,
         roll, curl, curlicue, ringlet, gyre, scroll]
    2: American chemist who with Richard Smalley and Harold Kroto
       discovered fullerenes and opened a new branch of chemistry
       (born in 1933) [syn: Curl, Robert Curl, Robert F. Curl,
       Robert Floyd Curl Jr.]
    3: a strand or cluster of hair [syn: lock, curl, ringlet,
       whorl]
    v 1: form a curl, curve, or kink; "the cigar smoke curled up at
         the ceiling" [syn: curl, curve, kink]
    2: shape one's body into a curl; "She curled farther down under
       the covers"; "She fell and drew in" [syn: curl up, curl,
       draw in]
    3: wind around something in coils or loops [syn: coil, loop,
       curl] [ant: uncoil]
    4: twist or roll into coils or ringlets; "curl my hair, please"
       [syn: curl, wave]
    5: play the Scottish game of curling

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "curl":
   arc, arch, bend, bend back, bow, catacaustic, catenary, caustic,
   circle, cirrus, coil, conchoid, corkscrew, crimp, crisp, crook,
   curlicue, curve, decurve, deflect, diacaustic, dome, ellipse,
   embow, entwine, evolute, festoon, flex, frizz, frizzle, gyre,
   helix, hook, hump, hunch, hyperbola, incurvate, incurve, inflect,
   involute, kink, lituus, lock, loop, parabola, ponytail, recurve,
   reflect, reflex, retroflex, ringlet, roll, round, sag, screw,
   scroll, sinus, spiral, swag, sweep, swirl, tendril, tracery, turn,
   twine, twirl, twist, vault, volute, volution, vortex, whirl, whorl,
   wind, wreathe