graveyard shift

Noun graveyard shift has 2 senses

• graveyard shift(n = noun.time) night shift - the work shift during the night (as midnight to 8 a.m.);
is a kind of duty period, shift, work shift

• graveyard shift(n = noun.group) night shift - workers who work during the night (as midnight to 8 a.m.);
is a kind of shift