The Collaborative International Dictionary of English v.0.48:

Hush \Hush\, n.
   Stillness; silence; quiet. [R.] "It is the hush of night."
   --Byron.
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   Hush money, money paid to secure silence, or to prevent the
      disclosure of facts. --Swift.
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The Collaborative International Dictionary of English v.0.48:

Hush \Hush\, a.
   Silent; quiet. "Hush as death." --Shak.
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The Collaborative International Dictionary of English v.0.48:

Hush \Hush\ (h[u^]sh), v. t. [imp. & p. p. Hushed (h[u^]sht);
   p. pr. & vb. n. Hushing.] [OE. huschen, hussen, prob. of
   imitative origin; cf. LG. hussen to lull to sleep, G. husch
   quick, make haste, be silent.]
   1. To still; to silence; to calm; to make quiet; to repress
      the noise or clamor of.
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            My tongue shall hush again this storm of war.
                                                  --Shak.
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   2. To appease; to allay; to calm; to soothe.
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            With thou, then,
            Hush my cares?                        --Otway.
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            And hush'd my deepest grief of all.   --Tennyson.
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   To hush up, to procure silence concerning; to suppress; to
      keep secret. "This matter is hushed up." --Pope.
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The Collaborative International Dictionary of English v.0.48:

Hush \Hush\, v. i.
   To become or to keep still or quiet; to become silent; --
   esp. used in the imperative, as an exclamation; be still; be
   silent or quiet; make no noise.
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         Hush, idle words, and thoughts of ill.   --Keble.
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         But all these strangers' presence every one did hush.
                                                  --Spenser.
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WordNet (r) 3.0 (2006):

hush
    n 1: (poetic) tranquil silence; "the still of the night" [syn:
         hush, stillness, still]
    v 1: become quiet or still; fall silent; "hush my baby!"
    2: cause to be quiet or not talk; "Please silence the children
       in the church!" [syn: hush, quieten, silence, still,
       shut up, hush up] [ant: louden]
    3: become quiet or quieter; "The audience fell silent when the
       speaker entered" [syn: quieten, hush, quiet, quiesce,
       quiet down, pipe down] [ant: louden]
    4: wash by removing particles; "Wash ores"
    5: run water over the ground to erode (soil), revealing the
       underlying strata and valuable minerals