shackle

Concise Oxford English Dictionary © 2008 Oxford University Press:
shackle/ˈʃakl/

▶noun

• 1 (shackles) a pair of fetters connected by a chain, used to fasten a prisoner's wrists or ankles together.

  ■ restraints or impediments.

• 2 a metal link, typically U-shaped, closed by a bolt and used to secure a chain or rope to something.

▶verb

• 1 chain with shackles.

• 2 restrain; limit.

– origin OE sc(e)acul ‘fetter’, of Gmc origin.