Troll plate

from The Collaborative International Dictionary of English v.0.48
Troll \Troll\, n.
   1. The act of moving round; routine; repetition. --Burke.
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   2. A song the parts of which are sung in succession; a catch;
      a round.
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            Thence the catch and troll, while "Laughter, holding
            both his sides," sheds tears to song and ballad
            pathetic on the woes of married life. --Prof.
                                                  Wilson.
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   3. A trolley.
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   {Troll plate} (Mach.), a rotative disk with spiral ribs or
      grooves, by which several pieces, as the jaws of a chuck,
      can be brought together or spread radially.
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