Shackle/ˈʃækl/ Definition 1 of 3Pro Tip 1/3Physical Restraint Refers to actual devices used to physically restrict someone’s movement. The guards fastened shackles around the prisoner's ankles. Pro Tip 2/3Historical Usage Shackles have historical ties to slavery and imprisonment. Historians describe how slaves were transported in shackles. Pro Tip 3/3Symbol of Oppression Metaphorically, shackles can represent a lack of freedom or oppression. Poets often use shackles as a symbol for lack of liberty.