If someone wakes up with a hangover, they feel sick and have a headache because they have drunk a lot of alcohol the night before.
N-COUNT
遗留观念（或习俗）
Something that is a hangover from the past is an idea or way of behaving which people used to have in the past but which people no longer generally have.
例句
As a hangover from rationing, they mixed butter and margarine.作为食品配给制的一种遗留影响，他们总把黄油和人造黄油混在一起吃。