disagreeable aftereffects from the use of drugs (especially alcohol)
"After staying out until dawn, I woke up with a pounding headache and nausea that was clearly a hangover from last night's heavy drinking."
Negative effects, such as headache or nausea, caused by previous drunkenness due to (excessive) consumption of alcohol.
"After last night's excessive drinking at the bar, I woke up today suffering from a terrible hangover that made it impossible to work."