The Collaborative International Dictionary of English v.0.48:

homework \homework\ n.
   1. preparatory school work done outside school (especially at
      home).

   Syn: prep, preparation.
        [WordNet 1.5]

   2. Hence: [fig.] Studies or other preparatory work done prior
      to some activity; -- usually used of preparations for
      activities of significance or consequence for the
      performer; as, the candidate didn't do her homework well
      and was outclassed in the debate.
      [PJC]

   3. Paid work done at home, especially piecework.
      [PJC]

WordNet (r) 3.0 (2006):

homework
    n 1: preparatory school work done outside school (especially at
         home) [syn: homework, prep, preparation]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "homework":
   assignment, busywork, chalk talk, chare, charge, chore, commission,
   discourse, disquisition, duty, errand, exercise, exposition,
   fish to fry, harangue, homily, instruction, job, job of work,
   labor, lecture, lecture-demonstration, lesson, make-work,
   matters in hand, mission, moral, moral lesson, morality,
   moralization, object lesson, odd job, piece of work, preachment,
   project, recital, recitation, sermon, service, set task,
   skull session, stint, talk, task, teaching, things to do, work