rewel bone

from The Collaborative International Dictionary of English v.0.48
Rewel bone \Rew"el bone`\ [Perh. from F. rouelle, dim. of roue a
   wheel, L. rota.]
   An obsolete phrase of disputed meaning, -- perhaps, smooth or
   polished bone.
   [1913 Webster]

         His saddle was of rewel boon.            --Chaucer.
   [1913 Webster]
    

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