Merriam-Webster Collegiate Dictionary - shackle

 I. noun  Etymology: Middle English schakel, from Old English sceacul; akin to Old Norse skokull pole of a cart  Date: before 12th century  1. something (as a manacle or fetter) that confines the legs or arms  2. something that checks or prevents free action as if by fetters — usually used in plural  3. a usually U-shaped fastening device secured by a bolt or pin through holes in the end of the two arms  4. a length of cable or anchor chain of usually 15 fathoms  II. transitive verb  (~d; shackling)  Date: 15th century  1.  a. to bind with ~s ; fetter  b. to make fast with or as if with a ~  2. to deprive of freedom especially of action by means of restrictions or handicaps ; impede  Synonyms: see hamper  • ~r noun