work for which a person is paid in cash, with the transaction not recorded or reported, so as to avoid paying income tax on the amount earned.
black•workPronunciation: (blak'wûrk"), [key]
embroidery done with black, usually silk, thread on white fabric, esp. linen. Also,black work.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.