galley slave

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A slave or convict forced to ply an oar of a galley.
• noun A person assigned to perform tedious or menial tasks; a drudge.

from The Century Dictionary.

• noun A person condemned for a crime to work at the oar on board a galley.
• noun A compositor, jocosely regarded as bound to the “galley.”

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A slave who rows in a galley.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a laborer who is obliged to do menial work
• noun a slave condemned to row in a galley