hard labor

HARD LABOR, punishment. In those states where the penitentiary system has 
been adopted, convicts who are to be imprisoned, as part of their 
punishment, are sentenced to perform hard labor. This labor is not greater 
than many freemen perform voluntarily, and the quantity required to be 
performed is not at all unreasonable. In the penitentiaries of Pennsylvania 
it consists in being employed in weaving, shoemaking, and such like 
employments. 
    

33 Moby Thesaurus words for "hard labor":
      arduousness, backbreaking work, burdensomeness, confinement,
      dismemberment, effortfulness, estrapade, galleys, hard job,
      hard work, impalement, imprisonment, incarceration, jailing,
      keelhauling, laboriousness, martyrdom, onerousness, oppressiveness,
      penal servitude, picketing, railriding, rock pile, strappado,
      strenuousness, tar-and-feathering, the gantlet, toilsomeness,
      torment, torture, troublesomeness, uphill work, warm work