[1] : The Collaborative International Dictionary of English v.0.48

slip ring \slip ring\ n.
   a metal ring on a rotating part of a machine to provide a
   continuous electrical connection through brushes on
   stationary contacts
   wordnet 1.5

[2] : WordNet (r) 2.0

slip ring
     n : connection consisting of a metal ring on a rotating part of
         a machine; provides a continuous electrical connection
         through brushes on stationary contacts

Annual Ring >> A Words
Annual Ring, definition of term: Annual Ring
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