from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A work shift that runs during the early morning hours, as from midnight to 8 A.M.
- n. The workers on such a shift.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A night shift in a factory or other place of work, especially one from midnight to 8 AM on a three-shift schedule.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the work shift during the night (as midnight to 8 a.m.)
- n. workers who work during the night (as midnight to 8 a.m.)
By association of the spooky, cold and silent properties of both the night and graveyards. (Wiktionary)