The Collaborative International Dictionary of English v.0.48:

Shower \Show"er\, n. [OE. shour, schour, AS. se?r; akin to D.
   schoer, G. schauer, OHG. sc?r, Icel. sk?r, Sw. skur, Goth.
   sk?ra windis a storm of wind; of uncertain origin.]
   1. A fall or rain or hail of short duration; sometimes, but
      rarely, a like fall of snow.
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            In drought or else showers.           --Chaucer.
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            Or wet the thirsty earth with falling showers.
                                                  --Milton.
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   2. That which resembles a shower in falling or passing
      through the air copiously and rapidly.
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            With showers of stones he drives them far away.
                                                  --Pope.
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   3. A copious supply bestowed. [R.]
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            He and myself
            Have travail'd in the great shower of your gifts.
                                                  --Shak.
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   Shower bath, a bath in which water is showered from above,
      and sometimes from the sides also.
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WordNet (r) 3.0 (2006):

shower bath
    n 1: booth for washing yourself, usually in a bathroom [syn:
         shower stall, shower bath]
    2: washing yourself by standing upright under water sprayed from
       a nozzle; "he took a shower after the game" [syn: shower,
       shower bath]