The Collaborative International Dictionary of English v.0.48:

Shaker \Shak"er\, n.
   1. A person or thing that shakes, or by means of which
      something is shaken.
      [1913 Webster]

   2. One of a religious sect who do not marry, popularly so
      called from the movements of the members in dancing, which
      forms a part of their worship.
      [1913 Webster]

   Note: The sect originated in England in 1747, and came to the
         United States in 1774, under the leadership of Mother
         Ann Lee. The Shakers are sometimes nicknamed Shaking
         Quakers, but they differ from the Quakers in doctrine
         and practice. They style themselves the "United Society
         of Believers in Christ's Second Appearing." The sect is
         now confined in the United States.
         [1913 Webster]

   3. (Zool.) A variety of pigeon. --P. J. Selby.
      [1913 Webster]

WordNet (r) 3.0 (2006):

shaker
    n 1: a person who wields power and influence; "a shaker of
         traditional beliefs"; "movers and shakers in the business
         world" [syn: shaker, mover and shaker]
    2: a member of Christian group practicing celibacy and communal
       living and common possession of property and separation from
       the world
    3: a container in which something can be shaken