The Collaborative International Dictionary of English v.0.48:

Quiet \Qui"et\, v. t. [imp. & p. p. Quieted; p. pr. & vb. n.
   Quieting.]
   1. To stop motion in; to still; to reduce to a state of rest,
      or of silence.
      [1913 Webster]

   2. To calm; to appease; to pacify; to lull; to allay; to
      tranquillize; as, to quiet the passions; to quiet clamors
      or disorders; to quiet pain or grief.
      [1913 Webster]

            Quiet yourselves, I pray, and be at peace. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Quiet \Qui"et\, v. i.
   To become still, silent, or calm; -- often with down; as, be
   soon quieted down.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quiet \Qui"et\, n. [L. quies, -etis. See Quiet, a.]
   [1913 Webster]
   1. The quality or state of being quiet, or in repose; as an
      hour or a time of quiet.
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   2. Freedom from disturbance, noise, or alarm; stillness;
      tranquillity; peace; security.
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            And join with thee, calm Peace and Quiet. --Milton.
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   At quiet, still; peaceful.

   In quiet, quietly. " I will depart in quiet." --Shak.

   Out of quiet, disturbed; restless. [Obs.] "She is much out
      of quiet." --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quiet \Qui"et\, a. [Compar. Quieter; superl. Quietest.] [L.
   quietus, p. p. pf quiescere to rest, keep quiet; akin to
   quies rest, and prob. to E. while, n. See While, and cf.
   Coy, a., Quiesce, Quietus, Quit, a., Quite,
   Requiem.]
   1. In a state of rest or calm; without stir, motion, or
      agitation; still; as, a quiet sea; quiet air.
      [1913 Webster]

            They . . . were quiet all the night, saying, In the
            morning, when it is day, we shall kill him. --Judg.
                                                  xvi. 2.
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   2. Free from noise or disturbance; hushed; still.
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   3. Not excited or anxious; calm; peaceful; placid; settled;
      as, a quiet life; a quiet conscience. " So quiet and so
      sweet a style." --Shak.
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            That son, who on the quiet state of man
            Such trouble brought.                 --Milton.
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   4. Not giving offense; not exciting disorder or trouble; not
      turbulent; gentle; mild; meek; contented.
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            The ornament of a meek and quiet spirit. --1 Pet.
                                                  iii. 4.
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            I will sit as quiet as a lamb.        --Shak.
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   5. Not showy; not such as to attract attention;
      undemonstrative; as, a quiet dress; quiet colors; a quiet
      movement.
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   Syn: Still; tranquil; calm; unruffled; smooth; unmolested;
        undisturbed; placid; peaceful; mild; peaceable; meek;
        contented.
        [1913 Webster]

WordNet (r) 3.0 (2006):

quiet
    adv 1: with little or no activity or no agitation (`quiet' is a
           nonstandard variant for `quietly'); "her hands rested
           quietly in her lap"; "the rock star was quietly led out
           the back door"; "sit here as quiet as you can" [syn:
           quietly, quiet] [ant: unquietly]
    adj 1: characterized by an absence or near absence of agitation
           or activity; "a quiet life"; "a quiet throng of
           onlookers"; "quiet peace-loving people"; "the factions
           remained quiet for almost 10 years" [ant: unquiet]
    2: free of noise or uproar; or making little if any sound; "a
       quiet audience at the concert"; "the room was dark and quiet"
       [ant: noisy]
    3: not showy or obtrusive; "clothes in quiet good taste" [syn:
       quiet, restrained]
    4: in a softened tone; "hushed voices"; "muted trumpets"; "a
       subdued whisper"; "a quiet reprimand" [syn: hushed,
       muted, subdued, quiet]
    5: (of a body of water) free from disturbance by heavy waves; "a
       ribbon of sand between the angry sea and the placid bay";
       "the quiet waters of a lagoon"; "a lake of tranquil blue
       water reflecting a tranquil blue sky"; "a smooth channel
       crossing"; "scarcely a ripple on the still water"; "unruffled
       water" [syn: placid, quiet, still, tranquil,
       smooth, unruffled]
    6: of the sun characterized by a low level of surface phenomena
       like sunspots e.g. [ant: active]
    n 1: a period of calm weather; "there was a lull in the storm"
         [syn: lull, quiet]
    2: an untroubled state; free from disturbances [syn:
       tranquillity, tranquility, quiet]
    3: the absence of sound; "he needed silence in order to sleep";
       "the street was quiet" [syn: silence, quiet] [ant:
       sound]
    4: a disposition free from stress or emotion [syn: repose,
       quiet, placidity, serenity, tranquillity,
       tranquility]
    v 1: become quiet or quieter; "The audience fell silent when the
         speaker entered" [syn: quieten, hush, quiet,
         quiesce, quiet down, pipe down] [ant: louden]
    2: make calm or still; "quiet the dragons of worry and fear"
       [syn: calm, calm down, quiet, tranquilize,
       tranquillize, tranquillise, quieten, lull, still]
       [ant: agitate, charge, charge up, commove, excite,
       rouse, turn on]