from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. work done in addition to one's normal duties
from the GNU version of the Collaborative International Dictionary of English
- n. Work aside from regular work; subordinate or secondary business.
from The Century Dictionary and Cyclopedia
- n. Work done at odd times or in addition to one's regular work; an occasional task or performance.
- n. A work that has failed in the doing; a work that has proved a failure.
From by- + work. (Wiktionary)
For naval service is a matter of art, like anything else; and does not admit of being practised just when it may happen, as a bywork; but rather does not even allow of anything else being a bywork to it.