to block a hole or pipe so that water, smoke etc cannot go through it
2British Englishinformalto stay up late:
Joe stopped up till 3 o'clock to watch the boxing.
GRAMMAR GRAMMAR Tostop doing something means to not continue an activity• It has stopped raining (NOT stopped from raining). • He couldn't stop talking about it (NOT stop from talking/stop to talk).Tostop to do somethingmeans to stand still, or stop what you are doing, in order to do something• He stopped to pick up a piece of paper.Tostop someone from doing somethingmeans to prevent someone from doing something• You can't stop me from going (NOT stop me to go). In British English you can leave out 'from'• This will help stop people dying of AIDS.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.