The Collaborative International Dictionary of English v.0.48:

anchylosis \an`chy*lo"sis\, ankylosis
\an`ky*lo"sis\([a^][ng]`k[i^]*l[=o]"s[i^]s), n. [NL., fr. Gr.
   'agky`lwsis, fr. 'agkyloy^n to crook, stiffen, fr. 'agky`los
   crooked: cf. F. ankylose.]
   1. (Med.) The process of formation of a stiff joint; also,
      the abnormal adhesion and rigidity of the bones of a joint
      which has become stiff. --Dunglison.
      [1913 Webster + AS]

   2. (Anat.) The union of two or more separate bones to from a
      single bone; the close union of bones or other structures
      in various animals.
      [1913 Webster]

WordNet (r) 3.0 (2006):

anchylosis
    n 1: abnormal adhesion and rigidity of the bones of a joint
         [syn: ankylosis, anchylosis]